By the end of May, the Second Pacific Squadron was on the last leg of its journey to Vladivostok, taking the shorter, riskier route between Korea and Japan, and travelling at night to avoid discovery. Unfortunately for the Russians, while in compliance with the rules of war, the two trailing hospital ships had continued to burn their lights, which were spotted by the Japanese armed merchant cruiser "Shinano Maru". Wireless communication was used to inform Togo's headquarters, where the Combined Fleet was immediately ordered to sortie. Still receiving reports from scouting forces, the Japanese were able to position their fleet to "cross the "T"" of the Russian fleet. The Japanese engaged the Russians in the Tsushima Straits on 27–28 May 1905. The Russian fleet was virtually annihilated, losing eight battleships, numerous smaller vessels, and more than 5,000 men, while the Japanese lost three torpedo boats and 116 men. Only three Russian vessels escaped to Vladivostok, while six others were interned in neutral ports. After the Battle of Tsushima, a combined Japanese Army and Navy operation occupied Sakhalin Island to force the Russians into suing for peace.