The campaign aimed to occupy the Baltic islands of Saaremaa (Ösel), Hiiumaa (Dagö) and Muhu (Moon).

The three islands were part of the Russian Empire and strategically dominated the central and northern Baltic Sea.

After two failed attempts, the German army landed on Hiiumaa (Dagö) on 12 October, capturing the island the following day.

The Russian Baltic Fleet had to withdraw from the Suur Strait after its losses at the Battle of Moon Sound.

After the revolutionary turmoil in Russia during the early part of 1917, the German high command believed capturing the islands would outflank Russian defences and lay Petrograd (St. Petersburg) vulnerable to attack.