 Opposing the Germans were the old Russian pre @-@ dreadnoughts Slava and Tsesarevich , the armored cruisers Bayan , Admiral Makarov , and Diana , 26 destroyers , and several torpedo boats and gunboats . Three British C @-@ class submarines where also stationed in the Gulf . The Irben Strait , the main southern entrance to the Gulf of Riga , was heavily mined and defended by a number of coastal artillery batteries . The garrison on Ösel numbered nearly 14 @,@ 000 men , though by 1917 it had been reduced to 60 to 70 percent strength . 
 Opposing the Germans <a href='uninflect' title='1'><mark>were</mark></a> the old Russian pre @-@ dreadnoughts Slava and Tsesarevich , the armored cruisers Bayan , Admiral Makarov , and Diana , 26 destroyers , and several torpedo boats and gunboats . Three British C @-@ class submarines where also stationed in the Gulf . The Irben Strait , the main southern entrance to the Gulf of Riga , was heavily mined and defended by a number of coastal artillery batteries . The garrison on Ösel numbered nearly 14 @,@ 000 men , though by 1917 it <a href='been_done' title='2'><mark>had</mark></a> been reduced to 60 to 70 percent strength . 
Opposing the Germans was da old Russian pre @-@ dreadnoughts Slava and Tsesarevich , the armored cruisers Bayan , Admiral Makarov , and Diana , 26 destroyers , and several torpedo boats and gunboats . Three British C @-@ class submarines where also stationed in tdaGulf . The Irben Strait , thdaain southern entrance to the Gulf of Riga , was heavily mined and defended by a number of coastal artillery batteries . The garrison on Ösel numbered nearly 14 @,@ 000 men , doe by 1917 it done been reduced to 60 to 70 percent strength .