Russia had opened their part of the war by invading the Swedish-held territories of Livonia and Estonia. Charles countered this by attacking the Russian besiegers at the Battle of Narva (November 1700). The Russians outnumbered the Swedish army of ten thousand men by almost four to one. Charles attacked under cover of a blizzard, effectively split the Russian army in two and won the battle. Many of Peter's troops who fled the battlefield drowned in the Narva River. The total number of Russian fatalities reached about 10,000 at the end of the battle, while the Swedish forces lost 667 men.