In 1174 Frederick reappeared in Italy, with a new army, and with hostile intentions against the revolted cities.  The Lombards had built a new city, in a locality surrounded by rivers and marshes, and had enclosed it with walls which they sought to make impregnable.  This they named Alexandria, in honor of the pope and in defiance of the emperor, and against this Frederick’s first assault was made.  For seven months he besieged it, and then broke into the very heart of the place, through a subterranean passage which the Germans had excavated.  To all appearance the city was lost, yet chance and courage saved it.  The brave defenders attacked the Germans, who had appeared in the market-place; the tunnel, through great good fortune, fell in; and in the end the emperor was forced to raise the siege in such haste that he set fire to his own encampment in his precipitate retreat.

On May 29, 1176, a decisive battle was fought at Lignano, in which Milan revenged itself on its too-rigorous enemy.  The Carocium was placed in the middle of the Lombard army, surrounded by three hundred youths, who had sworn to defend it unto death, and by a body of nine hundred picked cavalry, who had taken a similar oath.

Early in the battle one wing of the Lombard army wavered under the sharp attack of the Germans, and threw into confusion the Milanese ranks.  Taking advantage of this, the emperor pressed towards their centre, seeking to gain the Carocium, with the expectation that its capture would convert the disorder of the Lombards into a rout.  On pushed the Germans until the sacred standard was reached, and its decorations torn down before the eyes of its sworn defenders.

This indignity to the treasured emblem of their liberties gave renewed courage to the disordered band.  Their ranks re-established, they charged upon the Germans with such furious valor as to drive them back in disorder, cut through their lines to the emperor’s station, kill his standard-bearer by his side, and capture the imperial standard.  Frederick, clad in a splendid suit of armor, rushed against them at the head of a band of chosen knights.  But suddenly he was seen to fall from his horse and vanish under the hot press of struggling warriors that surged back and forth around the standard.

This dire event spread instant terror through the German ranks.  They broke and fled in disorder, followed by the death-phalanx of the Carocium, who cut them down in multitudes, and drove them back in complete disorder and defeat.  For two days the emperor was mourned as slain, his unhappy wife even assuming the robes of widowhood, when suddenly he reappeared, and all was joy again.  He had not been seriously hurt in his fall, and had with a few friends escaped in the tumult of the defeat, and, under the protection of night, made his way with difficulty back to Pavia.