 Complete the following phrase:  Later that summer, the Russians under Field Marshal Stepan Fyodorovich Apraksin besieged Memel with 75,000 troops. Memel had one of the strongest fortresses in Prussia. However, after five days of artillery bombardment the Russian army was able to storm it. The Russians then used Memel as a base to invade East Prussia and defeated a smaller Prussian force in the fiercely contested 