Interwar

1918 – 1939

Overview

The twenty-one years between the World Wars were not a period of military stagnation — they were a period of intense theoretical and practical weapons development. Armies that had survived the trenches debated what the next war would look like and invested accordingly. The results, for those who got it right, were decisive advantages in 1939–1941.

The major developments were the maturation of the tank and combined arms doctrine, the development of military aviation into a strategic weapon, and the refinement of automatic infantry weapons that shifted the balance from the rifle to the light machine gun and submachine gun.

Infantry Weapons

Semi-Automatic Rifles

The inefficiency of bolt-action rifles under fire — requiring the shooter to take the eye from the sight to cycle the bolt — drove development of semi-automatic (self-loading) rifles.

• M1 Garand — Adopted by the US Army in 1936; 8-round en bloc clip; gas-operated; the first standard-issue semi-automatic rifle for any major military; General Patton called it "the greatest battle implement ever devised"
• Soviet SVT-38/40 — Soviet semi-automatic in 7.62×54mmR; reliable but complex to manufacture
• German Gewehr 41/43 — German semi-automatics; the G43 was a capable weapon that arrived too late in numbers
• Johnson M1941 — American semi-automatic; used by USMC Raiders

Submachine Guns

Submachine guns — firing pistol-caliber ammunition from a fully automatic, compact platform — became standard issue for vehicle crews, paratroopers, and close-quarters troops.

• Thompson M1921/M1928 ("Tommy Gun") — American; .45 ACP; 20 or 50-round drum/stick magazines; used by US military, Prohibition gangsters, and British forces
• German MP 28 — Improved MP 18; 9mm; influenced many subsequent designs
• Bergmann MP 35 — German; 9mm; used by SS and exported widely
• Finnish KP/-31 (Suomi) — 71-round drum; highly influential on Soviet SMG design
• Soviet PPD-34/38 — Soviet 7.62×25mm; Suomi-influenced drum magazine

Light Machine Guns

• Browning Automatic Rifle (BAR) — American; .30-06; 20-round magazine; served as the squad automatic weapon for US forces
• Bren gun — British .303; 30-round curved top-mounted magazine; highly accurate; became the standard Commonwealth LMG
• German MG 34 — The first general-purpose machine gun (GPMG); could be used as a light or heavy MG; 900 rounds/minute; fed by drum or belt

Pistols

• Browning Hi-Power (P35) — Designed by John Browning, completed by Dieudonné Saive at FN; 9mm; 13-round magazine; one of the most successful pistol designs ever made
• Walther PP/PPK — German double-action semi-automatic; influential design
• Walther P38 — German service pistol intended to replace the Luger; double-action trigger

Tanks and Armored Vehicles

Tank Doctrine Debate

Two schools emerged from WWI tank experience:

1. Infantry support — Tanks attached to infantry to suppress machine guns (French and British orthodox view)
2. Independent armored formations — Concentrated armor with motorized infantry and aircraft support (Guderian's Panzerwaffe concept, Fuller and Liddell Hart in Britain)

Germany adopted the second approach. The results were demonstrated in Poland (1939) and France (1940).

Notable Interwar Tanks

• Renault FT — WWI design still in service with many nations into WWII
• British Vickers Medium Mk II — Standard British tank of the 1920s
• Soviet T-26 — Light tank based on the Vickers 6-ton; widely exported
• Soviet BT series — Fast tanks emphasizing speed; precursor to the T-34
• German Panzerkampfwagen I and II — Training and light tanks; inadequate for frontline combat but the vehicles Panzer doctrine was built around

Aviation

Military aviation matured rapidly in the interwar period:

• Biplane to monoplane transition — By 1939, all major air forces were converting to all-metal monoplane fighters
• Dive bombing — The German Junkers Ju 87 Stuka and American Douglas Dauntless demonstrated precision ground attack
• Strategic bombing theory — Giulio Douhet argued that strategic bombing could win wars independently; the RAF's Bomber Command and US Air Corps built forces around this concept
• Carrier aviation — The US Navy and Imperial Japanese Navy developed carrier doctrine that would prove decisive in the Pacific

Artillery and Other Weapons

• German 88mm FlaK 18/36 — Designed as an anti-aircraft gun; proved devastatingly effective as an anti-tank and field gun; one of the most versatile weapons of the era
• Anti-tank rifles — Heavy rifles firing hardened projectiles to penetrate tank armor; effective in the early war, obsolete by 1942
• Rocket artillery — Soviet Katyusha and German Nebelwerfer multiple-launch rocket systems were developed in this period

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