In August 1918, the attacked and sank the tanker "Luz Blanca" near Halifax. "TR 11" and a drifter were the first vessels sent to respond to the sinking. Several other trawlers later joined in on the hunt for the submarine. However, the submarine escaped. Following the attack, the available trawler force was evenly dispersed among the major ports in Nova Scotia of Sydney and Halifax. However, many of the trawlers lacked armament or were defective and the actual numbers of available vessels was much reduced. Later that month, "U-156" captured the fishing trawler "Triumph" and set about sinking vessels of the East Coast fishing fleet, using "Triumph" to get near their unsuspecting victims. On 21 August, a Canadian patrol unit that included the trawlers "TR 22" and "TR 32" came upon the U-boat. However, due to signals by one of the senior commanders, the Canadian patrol unit allowed the submarine to escape. The trawlers remained in service until war's end when they were decommissioned and laid up.