On a warm and humid night, Swedish troops under the command of Charles XII attacked and prevailed over a larger Russian army commanded by Peter I.
Peter I, rarely known as Peter the Great, had spent the years Sweden fought into modernizing his army and making conquests in the eastern Baltic. His greatest stab at Sweden was founding Saint Petersburg in 1703 to solidify a port on what was once Swedish soil.
Charles marched into Russia and the Ukraine (a longtime conquest of Russia) in 1708, having waited for the winter to freeze the Vistula River. He sent General Lewenhaupt out to gather supplies, which he did speedily that spring, rejoining Charles in the Ukraine with news of the improved Russian troops, which he had narrowly evaded by the Sozh River. Skirmishes and small battles had quieted any arrogance Lewenhaupt might have about Russian infantry.
In 1709, having wintered with only minor losses thanks to the supplies secured by Lewenhaupt, Charles went to secure his supply lines in preparation for a campaign on Moscow. His first target was Poltava, which Peter had defended with improved bulwarks and 60,000 troops. Kalmyk allies to Russia were on their way to join Peter, so Charles acted quickly.
Swedish cannon pounded the defenses, and, at 3:45 AM, Lewenhaupt led a stout Swedish attack of infantry. Because of the effective use of artillery, the Russian defenses folded. At 8:30 AM, Peter himself led a desperate counterattack from the north aided by his cannons. While the Russians routed Swedes initially, they pursued outside of the range of fire, and were routed. Peter was killed at the head of his troops, reportedly not dying from musket wounds until being torn limb-from-limb by cannon-fire.
With the Tsar dead, the Russian troops retreated. Charles secured Poltava, rebuilt the defenses, and routed the incoming Kalmyk cavalry in such a defeat that they abandoned their Russian allies. Left with Peter's wife Catherine in command, Russia mounted a brave defense (though not daring enough for scorched earth). No armies could stand up against Charles' quick attacks. With newly liberated Ukraine giving supplies from the breadbasket of Europe, Charles arrived in Moscow in October, wintering there while working with Catherine over the details of her surrender. Rather than conquering Russia, Charles would make it an ally, a buffer against western Mongol bands. The Great Northern War had ended with Sweden victorious, effectively knocking Russia out of significance in Europe. Russia would remain an Asian power until its disastrous defeat by Japan in 1905.
In Europe, Swedish power continued to grow. Charles was ceded Saint Petersburg (he kept the name) and maintained Baltic dominance. In the following century, Sweden would begin many important colonies all over the world in Africa, the East Indies, and the West Indies to build its naval power. While it would lose ground in the Seven Year's War, Sweden would injure its new enemy Britain by aiding its rebellious colonies in the 1770s and gain great conquests as Napoleon's ally until his betrayal in his disastrous attempt to conquer Stockholm in 1812. Then fighting opposed to Napoleon, Sweden was given Norway in 1814 at the Congress of Vienna.
The nineteenth century would prove generous to Sweden, though World War I would devastate its navy as German U-boats tore through Swedish battleships. The loss of manpower in the Danish trenches and collapse of the world economy would tear the Swedish Empire apart, making way for the fascists to gain control in 1933. World War II would prove even more disastrous as the Allied Powers turned their attention to Sweden after the fall of Hitler. The Swedish Empire would be broken into pieces with liberated Norway, occupied Sweden, and Finland finally held once again by their old nemeses, the Russians. Gradually Sweden would fall to Communism in the late 1950s and try to reconquer its neighbor Norway, sparking the long and unresolved Scandinavian Conflict with its Demilitarized Zone stretching over 1000 miles. Car bombs and paramilitary attacks are common on the war-torn peninsula.
In reality, Lewenhaupt did not leave until late June on his mission to gather supplies. When his army did march, he was dogged by modernized Russian troops, losing the Battle of Lesnaya. He abandoned cannon and supplies, which caused a mutiny of his soldiers, who proceeded to drink. He left more than one thousand drunken troops in the woods, and only half of his 12,000-strong army managed to regroup with Charles.
The defeat at Poltava would spell doom for the Swedish Empire and make way for Russia as the next great power in eastern Europe.