over the crippled Wiesbaden; during this period, König received a hit aft that caused significant damage. By the time the German fleet returned to the Jade estuary, the Nassau-class battleships , , and and the Helgoland-class battleships and took up guard duties in the outer roadstead. The Kaiser-class battleships , , and Prinzregent Luitpold, took up defensive positions outside the Wilhelmshaven locks. The four König-class ships, along with other capital ships—those that were still in fighting condition—had their fuel and ammunition stocks replenished in the inner harbor. Kronprinz was the only member of the class to emerge from the action undamaged. Subsequent operations König, Grosser Kurfürst, and Markgraf underwent repairs through July and then conducted training in the Baltic in August before taking part in the sortie that led to the action of 19 August 1916; during the operation, Markgraf and Grosser Kurfürst were temporarily attached to I Scouting Group as several of its battlecruisers had been badly mauled at Jutland and were still under repair. Scheer intended to bombard the British coast, but broke off after he received reports that the Grand Fleet was at sea; in the inconclusive action, German U-boats sank a pair of British light cruisers, and in return one German battleship was damaged by a mine. Further bouts of training in the Baltic, along with fruitless sweeps into the North Sea continued through the rest of 1916. During an operation to recover a pair of U-boats that had grounded off the Danish coast, a British submarine torpedoed Grosser Kurfürst and Kronprinz, though both ships returned to port for repairs. In 1917, the heavy units of the High Seas Fleet were largely restricted to guard duty in the German Bight, as the strategic priority of the German fleet had shifted to the U-boat campaign. During this period, the ships underwent refits that included the installation of the heavy tubular foremasts that Kronprinz had received when initially completed. In September, as the Imperial German Army prepared to attack the city of Riga in Russia, it requested assistance from the Navy to clear the Gulf of Riga to secure its seaward flank. The Navy transferred significant elements of the High Seas Fleet, including the four Königs, to conduct Operation Albion. The objectives included seizing the Baltic islands of Ösel, Moon, and Dagö, and destroying the Russian naval forces in the gulf, including the pre-dreadnought battleships and . The