The action of 17 May 1704 on Lake Peipus was the third of three small boat actions fought for control of Lake Peipus. The lake is on the border between Russian and Estonia, and at the start of the Great Northern War formed the border between Russia and Sweden. The two sides had very different fleets on the lake. The Swedes had a fleet of thirteen small naval warships, carrying 96 guns. In contrast the Russians relied on much larger numbers of small boats, generally used to carry troops in an attempt to board the Swedish ships. In battles in 1702 and 1703 the Swedish ships had defeated the Russian boats.
In 1704 the Russians tried a different tactic. The Swedish fleet was based at Dorpat, which was linked to the lake by the river Embach. The Russians landed a force of 9,000 soldiers at the mouth of the river. They blocked the river with a boom, and built gun batteries on shore to fire on the trapped Swedish ships.
On 17 May Loschern, the Swedish commander, fell into the Russian trap. Sailing down river towards the lake, the Swedish fleet ran into the boom and was trapped. With their manoeuvrability gone, the Swedish ships were vulnerable to attack by the swarm of Russian boats, and to fire from the gun batteries on the river bank. Despite the best efforts of the Swedish troops carried by the fleet, who briefly captured one of the gun batteries, the entire Swedish fleet was lost, some destroyed and some captured by the Russians. The soldiers managed to escape back upriver to Dorpat.
The destruction of the fleet on Lake Peipus left Dorpat itself vulnerable to attack. After a siege that lasted from 15 June to 25 July, the city fell to the Russians. At the end of the war in 1721 Dorpat, along with the rest of Estonia, remained in Russian hands.