Upon its completion, the boat was assigned to the Baltic Sea where she escorted, together with her sisters "T8" and , the light cruisers and as they supported German forces invading the Estonian islands of Ösel, Dagö and Muhu (Operation Beowulf) in mid-September. "T2", "T5", "T7", "T8" and "T11" were among the escorts for the Baltic Fleet, a temporary formation built around the battleship , as it sortied into the Sea of Åland on 23–29 September, to forestall any attempt by the Soviet Red Banner Baltic Fleet to breakout from the Gulf of Finland. Dagö was captured on 12–13 October, after "T7" is part of a decoy force used to distract the defenders. On 16 November, "T7", "T4" and departed Copenhagen, Denmark, en route to Cherbourg, France, to meet the commerce raider "Komet". The torpedo boats arrived on 25 November, and "Komet" reached Cherbourg the following day. The ships departed that night and arrived at Le Havre the following morning, where they waited for night to fall before proceeding. The British had spotted them and they were intercepted by motor torpedo boats (MTB) on 28 November, between Boulogne and Dunkirk. In a very confused night action, "T7" was machine-gunned by one of the MTBs, losing three dead and three wounded. On 3 December, "T4", "T7" and the torpedo boat rendezvoused with the commerce raider "Thor" and "T2" and "T12" in the Schillig Roads. Later that day, they began to escort "Thor" through the Channel. Delayed by heavy fog, the ships did not reach Brest, France, until the 15 December, while "Thor" continued onwards into the Atlantic. "T7" and "T12" sailed for Germany on 17 December, where the former was to begin another refit at Wesermünde.