I have to admit- this one is directly linked to news that popped up today.
Operation Albion was biggest and most successful naval landing operation conducted by German navy during WW1. The aim of this operation was to conquer islands of Saaremaa, Hiiumaa & Muhumaa (all located in boundaries of modern Estonia, that at the time belonged to Russian Empire). It lasted about a month in late 1917.
Strategically, those islands were considered unimportant until revolutions happened- german high command tought it would outflank russian positions & open door to St. Petersburg to press newly-risen communist leaders to end war. Secondary motive is likely to give german navy something to do after above-water fleet was sitting in harbour for almost 1,5 years after battle of Jutland.
Operation itself was successful. But it didnt bring consequence german high command was hoping- pushing Russia out of the war completely. That goal was achieved in early 1918 after germans occupied rest of Estonia, Latvia, Lithuania, Belarus & Ukraine, with navy approaching Petersburg.
Why this fact? Battlefield 1 DLC content was revealed- and russian DLC contains operation Albion. I am incredibly happy over it as it is only the 3rd time AAA game has included Estonia in (excluding games with grand map gameplay, such as Hearts of Iron or Total War). First 2 were Command & Conquer: Tiberian Dawn (2 missions, GDI campaign openings) and Splinter Cell: Blacklist. I am most happy about this particular entry though as i am complete history geek