World War I: German forces capture Tallinn to virtually complete the occupation of Estonia.

Tallinn is the capital and most populous city of Estonia. Situated on a bay in north Estonia, on the shore of the Gulf of Finland of the Baltic Sea, it has a population of 456,518 as of 2025 and administratively lies in Harju County. Tallinn is the main governmental, financial, industrial, and cultural centre of Estonia. It is located 187 km (116 mi) northwest of the country's second largest city, Tartu, however, only 80 km (50 mi) south of Helsinki, Finland; it is also 320 km (200 mi) west of Saint Petersburg, Russia, 300 km (190 mi) north of Riga, Latvia, and 380 km (240 mi) east of Stockholm, Sweden. From the 13th century until the first half of the 20th century, Tallinn was known in most of the world by variants of its other historical name Reval.

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, including the larger islands of Saaremaa (Ösel), Hiiumaa (Dagö), and Muhu (Moon).

February 25 is the 56th day of the year in the Gregorian calendar; 309 days remain until the end of the year.