the Courland Governorate for inner Russia. Courland was conquered by Germany in 1915 and included into the military Ober Ost administration. After the Russian surrender at the Treaty of Brest-Litovsk in 1918, the German Empire occupied the remaining Baltic provinces. The Ober Ost military administration began plans for German colonization of Courland. On April 20, 1917, the Commander-in-Chief of the Eastern front announced that 1/3 of arable land there should be reserved for settlement by German war veterans. This was approved by Courland's German nobility on September 22, 1917. United Baltic Duchy Livonian and Estonian nobles delivered a note of independence to Soviet representatives in Stockholm on January 28, 1918, announcing their intention to break away from Russia under the rights granted to them by the Treaty of Nystad of 1721. In response, the Bolsheviks, who controlled Estonia, arrested 567 leading Germans and deported them to Russia. After the signing of the Treaty of Brest-Litovsk they were allowed to return. Under German-Soviet treaties, Germany gained control over Courland, Riga, Saaremaa (Ösel), Livonia and Estonia. In the spring of 1918, Baltic Germans announced the restoration of the independent Duchy of Courland and Semigallia and pursued plans for uniting it with the Kingdom of Prussia. On April 12, 1918, Baltic German representatives from all Baltic provinces met in Riga and called on the German Emperor to annex the Baltic lands. Subsequently, a plan for a United Baltic Duchy ruled by Duke Adolf Friedrich of Mecklenburg, instead of outright annexation, was developed. Its regency council met on November 9, 1918, but collapsed with the German Empire. Independent Baltic states The Baltic Germans' rule and class privileges came to the end with the demise of the Russian Empire (due to the Bolshevik revolution of October 1917) and the independence of Estonia and Latvia in 1918–1919. Baltic Germans greatly suffered under Bolshevik regimes in Estonia and Latvia. While short-lived, they pursued Red Terror against Germans, often killing them purely because of their nationality. After the collapse of the German Empire, Baltic Germans in Estonia began forming volunteer units to defend against the Bolshevik threat. On November 27, 1918 this was authorized by the Estonian government, and the Volunteer Baltic Battalion (Freiwilligen Baltenbataillon) was formed under the command of Colonel Constantin von Weiss (de). During the Estonian and Latvian independence wars of 1918–1920, many Baltic Germans signed voluntarily into the newly formed Estonian and Latvian armies