On 2 May 1915 Lohs was promoted to Oberleutnant zur See. For one month Lohs was second radio officer on the battlecruiser Seydlitz, then he moved to U-Bootschule for two months. Afterwards he became a monitoring officer at the torpedo boat division. On 6 December he became commander of SM UC-75, on which he did 9 patrols along the British coast. On 2 January 1918 he became Commanding officer of UB-57, taking over the command of this boat from another legendary U-boat commander, Otto Steinbrinck. Lohs had also some very good ideas on U-boat warfare and new tactics and on 24 April 1918 he received the Pour le Mérite.
On 3 August 1918, he sailed from Zeebrugge for the last time. The last contact he made with the base was on the evening of 14 August as UB-57 was homeward bound roughly in the area of the Sandiette Bank, east of the Strait of Dover. Nothing more was heard. Lohs and 33 men lost their lives.UB-57 is believed to have run onto a mine. Lohs' body washed up on shore a week later and he is buried in the military cemetery at Vlissingen.
Lohs succeeded on 13 patrols in sinking 76 ships for a total tonnage of 149,465 gross register tons (GRT). He also damaged 17 other ships and sank the armed merchant cruiser HMS Moldavia.[1]
In the later Kriegsmarine, the 3rd U-boat Flotilla in Kiel was named after him.