Gatchina, with the city becoming one of the first centers of aviation and engine technology in Russia. The pilot Pyotr Nesterov was trained at the Gatchina airfield and made his first long-distance flight from Gatchina to Kiev. Gatchina Palace remained one of the official imperial residences of Tsar Nicholas II, who was presiding over annual military parades and celebrations of the Imperial Russian Army garrisons, stationed in Gatchina until 1917. World War I During World War I, major medical hospitals in Gatchina were visited by the Tsar Nicholas II and Empress Maria Fyodorovna, the mother of Nicholas II, his wife the Empress Alexandra Fyodorovna, as well as their daughters Grand Duchess Olga, Grand Duchess Tatiana, Grand Duchess Maria, and Grand Duchess Anastasia. In March 1917, the Russian Empire collapsed upon the abdication of Nicholas II following the February Revolution, leading to a decline in Gatchina's importance as the town and its palace became state property of the Russian Provisional Government, who converted it to a museum. Russian Civil War Shortly afterwards, the outbreak of the Russian Civil War saw Gatchina loyal to the White Movement, and the palace was visited by President Alexander Kerensky on October 27, 1917. During Kerensky's visit, fighting broke out in Gatchina between detachments of the Red Guards and Cossack units of General Pyotr Krasnov. The Reds won the battle, which had avoided the palace, and on November 1, they held a rally outside the palace in the main square, where Pavel Dybenko encouraged the Cossack units stationed in the palace to surrender and not to oppose the Red authorities. Kerensky left Gatchina Palace that night, and it was occupied by Red troops the following day. Interbellum In May 1918, the museum was re-opened by the Reds "for the victorious popular masses of the Russian Revolution" in Gatchina. From 1918 to 1941, the Gatchina Palace and parks were open to public as a national museum. On February 14, 1923, Gatchina was renamed Trotsk () by the new Soviet authorities, in honor of Leon Trotsky. After Joseph Stalin became General Secretary of the Communist Party of the Soviet Union, Trotsky was gradually exiled, and the town was renamed Krasnogvardeysk (, Red Guard City) on August 2, 1929. World War 2 Gatchina was occupied by Nazi Germany from Saturday, September 13, 1941, following the German invasion of the Soviet Union during World War II. The Germans renamed the