On 6 May, the IV Squadron ships were tasked with providing support to the assault on Libau. "Schwaben" and the other ships stood off Gotland to intercept any Russian cruisers that might try to intervene in the landings, which the Russians did not attempt. On 10 May, after the invasion force had entered Libau, the British submarines and spotted IV Squadron, but were too far away to make an attack. The increasingly active British submarines forced the Germans to employ more destroyers to protect the capital ships. As a result, "Schwaben" and her sisters were not included in the German fleet that assaulted the Gulf of Riga in August 1915, due to the scarcity of escorts. On 29 August, "Kapitän zur See" (Captain at Sea) Walter Engelhardt replaced Alberts aboard "Schwaben". She was then used as a guard ship in Libau, starting on 24 September. On 10–11 November, "Schwaben", her sisters and , and "Prinz Heinrich" left Libau, bound for Kiel.