The siege of Viborg took place in the spring of 1710 during the Great Northern War (1700–1721), as a second attempt by the Russians to capture the fortress port of Viborg (Vyborg), near the modern border between Russia and Finland, after a failed attempt in 1706. After the outbreak of the war, Swedish forces had fortified themselves in the port of Viborg. In order to assure safety for the newly founded city of Saint Petersburg, Peter the Great ordered the Swedish fort to be secured. A first unsuccessful attempt was made in 1706. Later plans were put on hold because of other ongoing conflicts but, after the Russian success at the Battle of Poltava in June 1709, the men and resources were available to capture the town.