In 1743, following the Russo-Swedish War of 1741–1743, part of the County of Kymmenegård and Nyslott, including the county capital of Villmanstrand, was ceded to Russia in the Treaty of Åbo. The remaining part of the county was merged in 1747 with some territories from County of Nyland and Tavastehus to a new County of Savolax and Kymmenegård. The county capital was moved to Lovisa.