"G9" was a member of the 10th Half-flotilla of the 5th Torpedo boat flotilla of the German High Seas Fleet on the outbreak of war. On 28 August 1914, the British Harwich Force, supported by light cruisers and battlecruisers of the Grand Fleet, carried out a raid towards Heligoland with the intention of destroying patrolling German torpedo boats. The German defensive patrols around Heligoland consisted of one flotilla (I Torpedo Flotilla) of 12 modern torpedo boats forming an outer patrol line about North and West of Heligoland, with an inner line of older torpedo boats of the 3rd Minesweeping Division at about . The 5th Torpedo boat flotilla, including "G9", together with four German light cruisers waited near Heligoland, and was ordered from Heligoland to investigate sightings of British submarines. "G9", at the head of the flotilla, sighted several ships ahead and the flash of guns, but uncertain whether the ships were friendly or enemies, continued to close until the unknown ships could be clearly identified as British destroyers, when she opened fire and turned turned away to escape the trap, as did the rest of the flotilla. The torpedo boat , which along with could not make full speed and lagged behind the rest of the flotilla, was hit by British shells before the arrival of the German cruiser allowed the 5th Flotilla to escape. The torpedo boat of the outer screen did not manage to evade the British force and was sunk. The intervention of the supporting British forces resulted in the sinking of the German cruisers , and . The British light cruiser and destroyers , and were badly damaged but safely returned to base. "G9" was undamaged.