The Battle of Breitenfeld was fought at a crossroads near the walled city of Leipzig on September 17, 1631. The battle lasted over six hours. The first two hours consisted of an exchange of artillery fire, followed by an Imperial attack with cavalry from both wings to both ends of the Protestant line. The cavalry attack routed the Saxon troops on the Swedish left flank. The imperial army conducted a general attack to exploit the exposed left flank. The Swedes repositioned their second line to cover the left flank and counterattacked with their cavalry. The attack on the Imperial left was led personally by Gustavus Adolphus, capturing the Imperial artillery and enveloping the Imperial left flank. The Swedes now had much greater weight of fire from their artillery, infantry, and the captured Imperial artillery. The Imperial line became disorganized under the heavy fire and was enveloped. Over 80% of Imperial forces were killed or captured. It was the Protestants' first major victory of the Thirty Years War. The Thirty Years' War was a series of wars in Central Europe between 1618-48. It was one of the longest and most destructive conflicts in European history, as well as the deadliest European religious war, resulting in eight million casualties.