The Heer is the Army's ground forces.
After the appearance of the tank at the end of World War I, the General Staff of the German Army (Heer) began to believe that a new war would be very different from any that had been fought up to that point. Due to the restrictions imposed by the Treaty of Versailles, experience with this new weapon was gained underground and in training camps in the Soviet Union. In preparation for World War II, a program was developed that centered on close cooperation between armored forces, aviation, and mechanized infantry. The program involved launching masses of tanks to break through enemy lines and wreak havoc in the rear under the cover of aviation. This aggressive, speed-based warfare became known as blitzkrieg. This was all based on training and new tactics because the first German tanks were not very well armored, and their weaponry was not particularly formidable; they relied mainly on speed on the battlefield.

At the start of the war, infantry weapons were a combination of traditional Mauser 98s and modern Maschinenpistole 1938s (MP38s), which were machine guns designed by Heinrich Vollmer. The 98k was an excellent bolt-action rifle that fired 7.92x57mm ammunition. The MP38, though expensive to produce, fired 9x19mm Parabellum ammunition and was suitable for close combat. After acquiring the Tokarev semi-automatic rifle from the Soviets, the Germans realized the need for a similar weapon. Mauser and Walther produced two unreliable models of the .41 rifle. In 1943, Walther proposed a new model combining the best features of its earlier G41 model with new developments. The Gewehr 43 entered service in 1944 and was renamed the Karabiner 43. Several new weapons were produced during the war, starting with the MP40. It had the same characteristics as the MP38 but was made of stamped and welded plates, making it less expensive to produce. Between 1941 and 1943, the Fallschirmjäger Gewehr 42, or FG42, an automatic rifle supplied to Luftwaffe paratroopers, was developed. Many consider it to be the first assault rifle in history. Around the same time, development of the Sturmgewehr 44 assault rifle began. Born from an early model called the MKb42, which later evolved into the MP43 and MP44, the Stg44 was a revolutionary weapon that changed the face of infantry warfare. The Soviet AK-47 was inspired by the MP-44 in both design and ammunition. These weapons became indispensable in close combat on battlefields where the German army was struggling and retreating on several fronts.

Concerning machine guns, the German Army entered the war with the Mauser Maschinengewehr 34, or MG34. It was fed by 200-round belts or 50-round assault magazines. A masterpiece of mechanics, the MG34 fired 7.92 x 57 mm ammunition at a rate of 1,000 rounds per minute. However, this Teutonic precision made it prone to malfunction, especially under critical conditions, due to the poor tolerances of the fine machining done entirely by lathe and milling machine. Not least among its disadvantages were the long production time and the resulting high cost.
The MG 42 was produced almost immediately and replaced the MG 34. The MG 42 proved to be an excellent squad machine gun. Built from stamped sheet metal, it was quick to build and reliable. It had a very high rate of fire of 1,200 rounds per minute and used the same ammunition and charges as the MG 34. The MG 42 was one of the best machine guns of its time and remains in service with several armies, including the Italian army, which uses the MG 42/59 model with NATO 7.62×51mm ammunition and a lower rate of fire of around 800 rounds per minute.

Due to the restrictions imposed on Germany by the Treaty of Versailles at the start of World War II, its artillery was modern in terms of its heavy, anti-aircraft, and anti-tank capabilities. As tanks became better armored and faster, anti-tank artillery evolved from 3.7 cm to 5 cm and 7.5 cm guns. By the time Germany entered the war, the 8.8 cm Flak 18 anti-aircraft guns had also proven effective against tanks. The 8.8 cm Pak 43 anti-tank gun entered service in 1943 and was mainly used in the North African theater alongside the Flak 18 and Flak 36. The latter two guns were too high, making them more exposed to enemy artillery fire. Anti-tank weapons became increasingly important on the battlefield as the Allies had thousands of medium-armored, fast tanks after America entered the war. Therefore, a simple, inexpensive, disposable personal weapon was designed and produced: the Panzerfaust, a hollow-charge rocket-propelled grenade launcher against a tank. Its five models had a useful range of 30 to 150 meters and could penetrate armor from 140 to 300 millimeters.

During the Polish and French campaigns, the principle of mobility was embodied by the 10-ton and 20-ton Pzkfw II and Pzkfw III tanks. The Pzkfw II was armed with a 20mm machine gun, while the Pzkfw III was armed with a 50/42mm cannon and had a supply of more than 90 rounds. Both could reach a road speed of 40 km/h, compared to 24 km/h on roads and 12 km/h on dirt roads for the British Matilda tanks. However, this speed advantage came at the expense of armor, the least important requirement in the tank design formula of mobility/firepower/protection. Also in the field were the 22-ton Pzkfw IV, which was armed first with a 75/24mm cannon, later with a 75/43mm and a 75/48mm. The tank had an escort of 80 rounds. The armor increased from 30 mm on the Pzkfw II and III to 80 mm on the Pzkfw IV, while maintaining a speed of 42 km/h on the road and 20 km/h off-road. This proves that the German idea was not only to use the vehicle for infantry support, but also as a weapon to break through enemy lines en masse and open the way for motorized infantry to conquer territory.

The Panzer IV was joined by the Pzkfw VI Tiger and the Pzkfw V Panther tanks.
The Tiger was designed to be superior to all enemy tanks.
Equipped with an 8.8 cm KwK 36 L/56 anti-tank gun, it entered service in 1942 and could pierce the armor of any British or American tank from over 1,500 meters away.
The Tiger had a 93-round reserve and 140 mm of frontal armor.
Powered by a 12-cylinder Maybach gasoline engine, it reached speeds of 40 km/h on paved roads and 20 km/h on dirt roads.
Its limitations were its weight of 57 tons, which made it unsuitable for rough terrain or weak bridges.
Production was progressively reduced beginning in 1944 due to the development of opposing anti-tank weapons.
The Soviet 122 mm gun and the British 25-pounder gun could pierce the Tiger's frontal armor at 1,500 meters. More than 1,300 Tigers were produced.

The Pzkfw V Panther, which entered service in 1943, was much lighter and more maneuverable than the Tiger. Designed to be more agile than the T-34 and more heavily armored than the Soviet KV-1, it was equipped with a 75/70mm gun, which had slightly inferior performance compared to the 88mm gun. Although it had a reserve of 82 rounds, it was powered by a 700 hp engine, like the Tiger. It had twice the range, reaching a speed of 46 km/h on the road and 30 km/h off-road, despite weighing 45 tons. More than 5,500 were produced.

Bibliography:
The German Assault Rifle 1935-1945 by Peter R. Senich
The German Machine Gun - Revised Edition - by Daniel D. Musgrave
Der Panzer-Kampfwagen PANTHER und seine abarten by Walter J. Spielberger
Panzerkampfwagen TIGER by Uwe Feist & Bruce Culver

The Luftwaffe, the airborne and paratroop forces of the Wehrmacht.

The Luftwaffe was formed during World War I when airplanes became useful on the battlefield. They were used to observe and report on enemy army movements and artillery dispositions, as well as to carry out dive bombing missions, since they were the most accurate mode in the absence of effective targeting devices.
The Luftwaffe was disbanded at the end of the war under the terms of the Treaty of Versailles. Despite the Treaty's prohibitions, a small air force was secretly established as early as 1926, and pilots were trained, primarily on civilian airline aircraft. The Luftwaffe was secretly re-established in 1933. Its existence was made public in March 1935, when Hitler placed Hermann Göring, a German ace from World War I, at the head of its supreme command.

Between 1936 and 1937, some contingents were sent to support General Francisco Franco's forces during the Spanish Civil War. This gave them the opportunity to refine techniques and propose aircraft upgrades, which helped secure Franco's victory and the establishment of his dictatorship. By the start of World War II, the Luftwaffe was the world's most powerful air force, with approximately 4,000 aircraft, including around 2,500 combat aircraft. These aircraft were at the heart of the German blitzkrieg in Poland and the Netherlands.

At the beginning of the war, the Junkers Ju87 Stuka (short for Sturzkampfflugzeug) dive bombers terrorized the populations of attacked and bombed cities and towns with the howl of their powerful sirens as they plunged to the ground. Although the aircraft was capable of extremely precise bombing at speeds of 350–390 km/h, it was very slow.
In the Battle of Britain, it was withdrawn from the skies due to numerous shootdowns by British Spitfires, which flew at speeds of 550–600 km/h.
Paradoxically, the Ju87 Stuka's successful dive-bombing experience in Spain led to the strategic undoing of the Luftwaffe and, consequently, Germany. Between 1932 and 1935, as Germany's military aviation was being developed, two schools of thought emerged.
One argued for the importance of high-altitude, four-engine strategic bombing, while the other argued that aviation should exclusively support ground troops and counter enemy aviation. It was precisely the experience in Spain that tipped the scales in favor of dive bombers and away from large strategic bombers, such as the Ju89 and Do19.

From 1939 to 1945, Germany produced over 50,000 fighter aircraft, including over 30,000 Messerschmitt Bf 109s and over 20,000 Focke-Wulf Fw 190s. The initial Bf 109s, which flew from 1935 to 1936, were not very fast and had Junkers engines with only about 600 horsepower. The Bf 109 did not become an aircraft that could keep up with the enemy until 1938, when Daimler Benz developed V-shaped axial engines that could produce up to 1,800 hp in the DB 605 version. The specific armament varied according to the required version. The Bf 109 surpassed the enemy in climb speed and acceleration. Most importantly, it could dive immediately without losing fuel flow to the engine because it was powered by direct injection. The Focke Wulf 190, which entered service in 1941, was equipped with a 1,600 hp BMW 801C radial engine. It was faster than the Spitfire and had a different engine configuration than the Bf 109. Its armament consisted of two 13mm machine guns and a 20mm cannon, making it excellent. Multirole aircraft were used as bombers and torpedo bombers. In the fighter class, the Messerschmitt Bf 110 was a twin-engine heavy fighter that was often used as a night fighter late in the war. It entered service in 1938, powered by a DB601 engine, and later by a DB605 engine. The specialized night-fighter version had a radar onboard and was armed with four MG 17 machine guns and two 20 mm cannons. Two more cannons were added to the rear of the cockpit to fire upward, as the German tactic was to attack Allied aircraft from behind and at a lower altitude.

It was also used as a bomber escort but was less maneuverable than single-engine fighters. Another heavy night fighter that defended Germany was the Junkers Ju88.
The twin-engine prototype flew in 1936 and entered service the same year. Initially designed as a light bomber, it evolved into a multirole aircraft, initially powered by two 1,200 hp Jumo 211s and later by two 1,700 hp BMW 801D-2s. The bomber version could carry up to 1,800 kilograms (4,000 pounds) of bombs, while the fighter version could carry up to 2,400 kilograms (5,300 pounds) in overload. About 3,000 fighter versions were produced.
The C-6 model was equipped with a radar similar to that of the Bf 110 and shared its armament. The Ju 88 was a mainstay of the Luftwaffe during World War II, as was the Heinkel He 111, a twin-engine, medium-range bomber that first flew in 1935. It was initially powered by two DB 600 engines, and later by Jumo 211s. Heavily armed, the He 111 could carry 2,000 kg of bombs, and more than 7,000 were produced. It was often used to tow gliders.

Messerschmitt 163. The first rocket plane in history.
It was the first rocket-powered, piloted aircraft in history to be used in combat, and it disappointed expectations that it would succeed in solving Germany's defensive problems by stopping the Allied bombers that were ravaging German cities in large numbers.
The Messerschmitt 163 was a stubby aircraft with a wingspan of 9.32 meters and a length of only 5.84 meters. Born as an interceptor fighter, originally equipped with a Walter HWK 509 A1 or A2 rocket engine, it could fly at a speed of more than 900 km/k at an altitude of 3,000 meters. Designed by Alexander Lippisch, it entered service in 1944 after nearly four years of development and testing. It was essentially a tailless glider whose engine provided enough thrust to allow it to quickly gain altitude and make a brief attack on Allied bomber formations with its two 30 mm cannons. When the fuel ran out, the engine would shut down and the aircraft would land as a glider. The main landing gear was released at the end of the take-off and the landing was made with a central skid. The Me 163 eventually proved to be more dangerous to pilots than to Allied aircraft: difficult to fly, susceptible to explosion due to its fuel consumption, and most importantly, vulnerable to fighter aircraft, especially when models with sufficient range to escort bomber groups into the heart of Germany came into production. By the end of the Second World War, some 300 Me 163s were in service.

Messerschmitt 262. The precursor of modern jet fighters.
The Messerschmitt 262 was the first jet aircraft to enter active service.
Dr. Richard Voigt conceived the project in 1938, and the plane's distinctive design was ready by spring 1941. Unfortunately, the engines were delayed.
The first test flight of the prototype occurred on April 18, 1941, with a 690-hp Jumo 210G propeller engine. It was not until July 18, 1942, that the aircraft was equipped with 840-kg Junkers 109-004A engines and rear landing gear, according to the traditional fighter design. The aircraft was designed with arrow wings intended for high speeds.
According to the manufacturer, Messerschmitt, the aircraft had fighter characteristics rather than reconnaissance characteristics, as originally intended.
The engines were an obvious obstacle to the final realization of the design due to their low power, which was still uncompetitive with that of the Bf 109G and propeller-driven Fw 190.

The innovative design of the aircraft prevented the project from being shelved. In May 1943, ace pilot Adolf Galland flew a prototype and declared that the aircraft was "propelled by an angel." He requested priority in its completion. Construction difficulties were not overcome until November 1943, when a retractable front undercarriage was installed and engine power was increased to 900 kg, making the aircraft more efficient and reliable.

Despite constant Allied bombing of German factories, production never exceeded sixty planes per month. Hitler believed that the plane could be more useful in ground combat against the Allied advance because it could carry about 1,000 kilograms of bombs, given the strong fears of invasion in Europe already present in the upper echelons of the Wehrmacht. This resulted in an unnecessary and wasteful debate over whether to use the extraordinary aircraft in fighter missions against the mass of Allied bombers already attacking German soil or as a fast bomber. However, with the advent of American high-altitude bombers that could not be countered by anti-aircraft artillery and were escorted by fast, modern P-51 Mustangs, the Me 262's ultimate fate was sealed as a fighter against swarms of more than 1,000 Allied aircraft that were pounding cities and industries daily as they moved further inland over German soil. This made the war's outcome seem desperate. Hitler's anger was compounded when he learned from Göring, the commander of the Luftwaffe, that the planned bomb load could not be transported. This resulted in revised deployment plans and a consequent delay in plans to defend German soil.
It wasn't until November 1944 that it became clear the Me 262 was better suited for hunting than bombing, so additional tanks were installed to increase its range.

The final version was a fighter, nicknamed the Schwalbe (Swallow), instead of a bomber, nicknamed the Sturmvogel (Storm Bird), and a two-seater trainer aircraft. Another major problem was preparing the pilots, who came to training on the fast jets with either brief experience on fighters or, for the more experienced pilots, on slower but more disciplined bombers. They generally chose to train and operate the latter.
Flying the Me 262 required great skill due to its superior speed and lower maneuverability compared to widely experienced, efficient German propeller planes of the time. Takeoff and landing were also delicate moments, causing a great loss of life and Me 262s. Allied fighters lurked within sight of the runways, which were built of concrete to support the weight of the aircraft and the heat produced by their engines, and attacked them.
Several versions entered active service. The first was equipped with 30 mm cannons, which were later increased to 50 mm with a range of up to 1 km. Later developments equipped the Me 262 with 24 R4M rockets mounted under the wings. However, the night fighter version was equipped with a radar, which reduced its performance and speed. The limited use of this exceptional aircraft did not change the outcome of the war, and its late entry into service was not decisive. This was partly due to the extensive protection of bomber fleets by fast, maneuverable P-51s, which also had good success against the slower, less maneuverable Me 262. Of the 1,433 Me 262s built, only 600 were in service by the end of the war due to frequent maintenance needs and a high accident and failure rate.

V1 and V2. The terror weapons of the Third Reich

The rivalry between the Luftwaffe and the Heer arose when the latter declared the V2 an artillery weapon, making it the Army's responsibility. This led the Luftwaffe to develop the V1 flying bomb. (Vergeltungswaffe 1 — Retaliatory Weapon 1).
The first experiments with the V1, which was designed by Fritz Gosslau and Robert Lusser, date back to 1941. It was not until June 1944 that the first flying bomb struck London. Powered by a pulsed jet engine, the Argus As014 could reach speeds of up to 640 kilometers per hour and had a range of about 300 kilometers. It carried a 900-kilogram warhead of conventional explosives. Approximately 30,000 V1 flying bombs were produced, 10,000 of which were aimed at England. It was easily intercepted by British Spitfires because it was not very fast. The Spitfires could shoot the V1 down with onboard weapons or bump it off the wing. Theoretically, the V1 could only be used as a saturation weapon—light and cheap—provided that a large number could be launched at once. The device could be launched from either a He 111 aircraft or a ramp with a clearly defined length, direction, and inclination, depending on the target. A gyrocompass and gyroscope controlled the pitch and yaw. When an odometer operated by a vane anemometer set at the start in relation to the estimated wind distance reached the estimated number of revolutions, the fuel flow was interrupted, and the V-1 crashed.

The development of the V2 rocket (Vergeltungswaffe 2), considered the first ballistic missile in history, was different. Its designer, Wernher von Braun, began his career in 1934 with the launch of the A2 rockets, followed by the A3 rockets.
These rockets were propelled by a rocket engine fueled by ethyl alcohol, liquid oxygen, hydrogen peroxide, and sodium permanganate, with water acting as a catalyst.
However, guidance systems were still very rudimentary, and all launches failed.

As the war approached, the military intervened in the development and construction of this weapon, which could deliver 1,000 kilograms of explosives to targets up to 400 kilometers away at a speed of over 5,000 kilometers per hour and at an altitude of about 90 kilometers, making it undetectable by any existing aircraft or weapon.

The first flight of the A4 model, renamed the V2 rocket, failed on June 13, 1942. However, the successful third launch on October 3, 1942, greatly advanced the development and production of this modern-era precursor in military and space technology.
The first V2 rocket was launched over London a few months after the V1 flying bomb.

Just under 5,000 were produced. The fuel shortage that plagued Germany in 1944 and the systematic destruction of launch sites by Allied bombers prevented this weapon from being used for massive attacks on England.

Bibliography:
Bombers of the Luftwaffe by Joachim Dressel and Manfred Griehl
German Aircraft of World War II by Al and Smith Kay
The LUftwaffe - a History by John Killen

The Kriegsmarine, U-boats and pocket battleships.
The Treaty of Versailles had prohibited Germany from arming itself with submarines and limited the displacement of new ships to 10,000 tons. Thus began the construction of the so-called "pocket battleships." The most famous of these was the Admiral Graf Spee. Designed in 1932 and commissioned in January 1936, she was scuttled by her commander on December 17, 1939, at the edge of territorial waters opposite the port of Montevideo, after the Battle of the River Plate. The Deutschland and the Admiral Scheer, sister ships designed in 1928 and 1931, respectively, and commissioned in 1933 and 1934, respectively, joined her. These ships had a displacement of about 12,000 tons, or 16,000 tons when fully loaded, and could reach speeds of 29 to 30 knots. They were compact yet technologically advanced, and their performance was equal to that of the classic battleships of the time. They were armed with six 28 cm guns in two triple turrets, eight 15 cm guns, eight 3.7 cm guns on four twin mounts, and ten 2 cm machine guns.

In June 1935, England and Germany signed a treaty that allowed Germany to build submarines and other types of ships prohibited by the Treaty of Versailles. The only restriction was that the strength of the German navy could not exceed 35 percent of England's navy.
As a result, two battlecruisers, the Scharnhorst and the Gneisenau, were put in the pipeline.
They were commissioned in January 1939 and May 1938, respectively, before the outbreak of war.
These 32,000-ton ships (39,000 tons fully loaded) could reach a speed of 31 knots.
They were equipped with nine 28 cm guns in three twin turrets, twelve 15 cm guns in four twin and four single turrets, fourteen 10.5 cm guns in seven twin turrets, sixteen 3.7 cm guns in eight twin turrets, and thirty-eight 2 cm machine guns.
When the Kriegsmarine entered the war, its strategic objective was to sink as much of England's merchant shipping tonnage as possible.

This tonnage supplied England with equipment and raw materials from overseas colonies and the United States.
Reduced supplies could cause serious difficulties for the British Empire, leading to its surrender.
In 1939, the German Navy had three "pocket battleships," two battlecruisers, eight cruisers, and 22 destroyers. The battleships Bismarck and Tirpitz entered service in August 1940 and February 1941, respectively.
They displaced 42,000 tons, or about 52,000 tons when fully loaded, and could reach a speed of 30 knots.
They were armed with eight 38 cm guns in four twin turrets, twelve 15 cm guns in six twin turrets, sixteen 10.5 cm guns in eight twin turrets, sixteen 3.7 cm guns in eight twin turrets, and forty-six 2 cm machine guns, as well as eight 533 mm torpedo tubes.
The 15,000-ton heavy cruiser Prinz Eugen entered service in August 1940, and 15 more destroyers were commissioned during the war.

The aircraft carrier Graf Zeppelin was never completed.

The German Navy's battleships were superior in armor and targeting systems.
Some British ships were sunk by hits from German battleships and heavy cruisers that pierced the horizontal armor up to the Santabarbara, causing the ammunition stores to explode.
However, the battleships did not have much luck against the British fleet. The Bismarck, for example, was sunk on May 27, 1941.
It was almost motionless due to a jammed rudder caused by a torpedo from an aircraft torpedo bomber.
This occurred after it took nearly 400 hits from the bulk of the British fleet, including the battleships Rodney and King George V.

 However, the main action was developed by the German Navy below the surface of the sea.

The threat of German U-boats forced the British and U.S. navies to escort supply convoys across the Atlantic to England and, later, the Soviet Union. According to the 1935 treaty between England and Germany, the latter could have a submarine fleet of up to 45 percent the size of England's. Early submarines were designed to operate on the surface, temporarily submerging to launch an attack or to remain undetected. The sinking of enemy cargo ships was often accomplished by gunfire rather than by torpedoes. The central model during the war, the Model VIIC submarine, was cramped and claustrophobic. It had a submerged displacement of 886 tons, was nearly 67 meters long, and had five 533-millimeter torpedo tubes and 14 torpedoes. They could reach a speed of 17 knots while surfacing, but this dropped to 7.5 knots while submerged with the aid of electric motors. They were equipped with an 8.8 cm gun and a 2 cm machine gun.

After France surrendered, U-boats could operate from ocean bases on the French Atlantic coast, such as Lorient and St. Nazaire, without risking interception and sinking by the Royal Navy in the English Channel or being stranded at bases in Germany, as occurred in World War I.
England, on the other hand, did not equip itself with patrol aircraft with sufficient range to cover the Atlantic. Additionally, all navies, including the Royal Navy, did not consider submarines to be a real threat. At the beginning of the war, merchant ships were immediately grouped into convoys and escorted by aircraft and anti-submarine warships as far as possible. However, the German naval services were able to decode messages from the British merchant marine, knowing where the convoys would form. A submarine would follow the convoy, wait for others to reach the area, and then attack in a formation called a wolf pack. At the turn of 1940 and 1941, ocean-going submarines using wolf pack tactics and the Luftwaffe using long-range Fw 200 aircraft sank hundreds of thousands of tons of shipping.

In mid-1941, the British acquired long-range patrol planes, including American Catalinas that were transferred to England under the Lend-Lease Act. They subjected the crews to specific and intensive training, which resulted in a marked improvement in convoy defense. Defense at sea improved due to an increase in escort ships, the entry into service of U.S. destroyers ceded to the Royal Navy, improved sonar, radar capable of intercepting surface-level submarines, and anti-submarine training. In December 1941, the aircraft carrier Audacity began escorting convoys as well.
As the Germans faced increasing difficulties in the North Atlantic, U-boat action shifted in early 1942 to the eastern seaboard of the United States, which had entered the war after the Japanese attack on Pearl Harbor. The U.S. Navy was caught completely unprepared. The Germans could intercept all merchant radio traffic. Ships sailed with their lights on, and the coast was illuminated by street and house lights. It was a disaster. Over 3,500,000 tons of shipping were sunk in six months.

By the end of 1942, convoys were equipped not only with escort ships but also with support ships capable of hunting U-boats. Air cover was provided by the newly commissioned B-24 Liberator bombers equipped with the latest radar. They could detect the small snorkel of a diving U-boat at periscope height while it was changing air and recharging its batteries. Despite the invention of the acoustic torpedo, the Germans had lost the technological race. They were also outmatched tactically by the Allies, who were sinking more U-boats than Germany could produce. This was partly due to Allied bombing of French factories and shipyards.

Germany produced more than 1,100 submarines and lost nearly 790. Most importantly, an estimated 30,000 sailors lost their lives aboard the U-boats.