The Solothurn ST-5 is a 20 mm

anti-aircraft gun Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

designed by Solothurn in Switzerland which ultimately was the design basis for the highly successful 2 cm FlaK 30 series of guns used by Germany in

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. Solothurn was owned by the German firm

Rheinmetall Rheinmetall AG is a German automotive and arms manufacturer, headquartered in Düsseldorf, Germany. Its shares are traded on the Frankfurt stock exchange. History Rheinmetall was founded in 1889. Banker and investor Lorenz Zuckermandel L ...

, which at the time was prohibited from developing certain weapons. It and other German manufacturers sought partnerships with foreign firms, often owning them outright, in an effort to circumvent the terms of the

Versailles Treaty The Treaty of Versailles (french: Traité de Versailles; german: Versailler Vertrag, ) was the most important of the peace treaties of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June ...

. The ST-5 fired the 'Long Solothurn' ammunition, the cartridge 20 × 138 mm. B. The cartridge case was 138 mm long, making it the most powerful 20 mm round available.

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* - While Germany did not adopt the ST-5, the Kriegsmarine did acquire a version of the weapon for ship-board air defense. The weapon was designated 20 mm C/30 and equipped several German naval vessels during World War II. This weapon was further refined for the other German forces as the 2 cm Flak 30 described separately. * - During the Second Sino-Japanese War (World War 2 in China), the Chinese Nationalist Army soldiers used the Solothurn ST-5 as the main AA gun. The Solothurn ST-5 firstly joined the

Battle of Shanghai The Battle of Shanghai () was the first of the twenty-two major engagements fought between the National Revolutionary Army (NRA) of the Republic of China (ROC) and the Imperial Japanese Army (IJA) of the Empire of Japan at the beginning of th ...

and the

Battle of Nanking The Battle of Nanking (or Nanjing) was fought in early December 1937 during the Second Sino-Japanese War between the Chinese National Revolutionary Army and the Imperial Japanese Army for control of Nanking (Nanjing), the capital of the Repub ...

. The Solothurn ST-5 was not only used for anti-aircraft and also used for destroying the Japanese tanks and armored vehicles, so it became the anti-tank gun in the Battle of Taierzhuang and destroyed 15 Japanese tanks in this Battle. * *

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See also