on the submarine. On 28 March 1917, Zinnia was escorting the tanker out of Queenstown when the submarine torpedoed and sunk Gasfa. Zinnia retaliated with two depth charges, which the submarine's crew considered "uncomfortably close", but the submarine escaped. Seven of Gasfas crew were killed in the attack, with the remainder rescued by Zinnia. On 3 May 1917, the German submarine torpedoed the British steamer West of Ireland. Zinnia came to Frederick Knights assistance, forcing the submarine to submerge, but could not stop the submarine torpedoing the merchant ship again, sinking Frederick Knight. The next day, U-62 stopped the Danish barque Jörgen Olsen, and attempted to sink the sailing vessel with gunfire. Zinnia again interrupted U-62, opening fire and forcing the submarine to submerge. Jörgen Olsen remained afloat and was towed into Berehaven. On 7 June 1917, the Q-ship was on patrol off the south coast of Ireland when she was torpedoed by the German submarine . Part of Pargusts crew abandoned ship as a "panic party", in order to tempt the submarine to surface, which UC-29 did after thirty minutes. Pargust then opened fire, sinking UC-29. Zinnia, the sloop and the American destroyer came to the assistance of Pargust which was kept afloat by her cargo of timber, with Crocus towing Pargust into Queenstown, with Zinnia and Cushing in escort. On 20 August 1917, Zinnia collided with the American destroyer , badly damaging the American ship, which was towed into Queenstown by Zinnia. Zinnia remained part of the First Sloop Flotilla at the end of the war. Belgium On 19 April 1920, Belgium bought the Zinnia as a fishery protection vessel, acquiring her without armament, although by 1923 she was listed as carrying one 4.7 inch gun and three 12-pounder (76 mm) guns. Belgium disbanded its Navy as a military force in 1927, but Zinnia remained in use as a civilian-manned fishery protection vessel. In May 1940, as Belgium fell to advancing German forces, the ship was seized by the German Army at the port of Ostend. She was reconstructed at the Antwerp shipyard of the Belgian shipbuilders Cockerill as an artillery training ship, with the forward well deck of the ship filled in to give a long forecastle that ran most of the length of the ship, an rebuilt superstructure and a new armament, and renamed Barbara. This armament consisted of a single 10.5 cm SK L/45 naval