German occupation of Estonia during World War I

Estonia was under military occupation by the German Empire during the later stages of the First World War. On 11–21 October 1917, the Imperial German Army occupied the West Estonian archipelago (Moonsund archipelago), including the larger islands of Saaremaa (Ösel), Hiiumaa (Dagö), and Muhu (Moon).

Fighting in Estonia ceased whilst negotiations over the Treaty of Brest-Litovsk took place. These broke down in February 1918,^[1]: 19 and to put pressure on the new Bolshevik regime of Soviet Russia to sign the Treaty of Brest-Litovsk, the Germans landed on the mainland of Estonia on 18 February 1918 and marched on Haapsalu (Hapsal) on 21 February 1918. The German forces occupied Valga (Walk) on 22 February, and Pärnu (Pernau), Viljandi (Fellin) and Tartu (Dorpat) on 24 February. Tallinn (Reval) was occupied on 25 February 1918, and in the rest of the Estonian mainland the last town captured by German forces was Narva (Narwa) on 4 March 1918. For the time being, the German advance put an end to both the Estonian Provisional Government which had declared the country independent on 24 February 1918 in Tallinn, as well as to the remaining Bolshevik Russian Red Guards in Estonia. The last Red Guards escaped to Russia over the Narva river on 5 March 1918.

Lieutenant General Adolf von Seckendorff arrived in Tallinn on 28 February 1918. He had acted as military commander of the 3rd Kommandatur at the head of the German military administration of the West Estonian archipelago. Later in 1918, with the signing of the Treaty of Brest-Litowsk, the Russian Bolshevik government renounced all claims of sovereignty over Estonia, formally giving the German Empire the right to either annex, or create a client state in, Estonia.^[1]: 19 Estonia became part of the German Ober Ost (military administration for Curonia, Estonia, Livonia, Ösel, and Riga) until the end of World War I in November 1918.