Lake Peipus lies on the border between Russia and Estonia. At the start of the Great Northern War (1702), the west bank was part of Sweden, the east part of the Russia of Peter the Great. On 31 May four small Swedish ships, carrying 42 guns between them, were attacked by a force of nearly 100 smaller Russian boats in the narrow strait that divides the lake into two halves. The Swedes generally had the better of the encounter, sinking three of the boats, but were forced to withdraw from the strait. Over the next two months the Russians were able to pick off two of the Swedish ships in isolated skirmishes, before both sides returned to their main bases in the area – the Swedes to Dorpat, the Russians to Pskov.