The battle of Legnano was a battle between the imperial army of Frederick Barbarossa and the troops of the Lombard League on 29 May 1176, near the town of Legnano, in present-day Lombardy, Italy. Although the presence of the enemy nearby was already known to both sides, they suddenly met without having time to plan any strategy. The battle was crucial in the long war waged by the Holy Roman Empire in an attempt to assert its power over the municipalities of northern Italy, which decided to set aside their mutual rivalries and join in a military alliance symbolically led by Pope Alexander III, the Lombard League.