On 25 May 1942, Japanese forces landed in Tacloban, signalling the beginning of their two-year occupation of Leyte. They fortified the city and improved its airfield. Since San Pedro Bay was ideal for larger vessels, the Japanese Imperial Naval Forces made Tacloban a port of call and entry. This time was considered the darkest in the history of Tacloban and the country due to the incidences of torture among civilians, including the elderly. In response, guerrilla groups operated in Leyte – the most notable of which was the group of Ruperto Kangleon.