Dispositions Colonna had meanwhile relocated to a formidable new position: the
manor park of Bicocca, about four miles (6 km) north of Milan. The park was situated between a large expanse of marshy ground to the west and the main road into Milan to the east; along this road ran a deep wet ditch, which was crossed by a narrow stone bridge some distance south of the park. The north side of the park was bordered by a sunken road, which Colonna deepened, constructing an earthen rampart on the southern bank. The entire length of the north side of the park was less than , allowing Colonna to place his troops quite densely; immediately behind the rampart were four ranks of Spanish
arquebusiers, commanded by
Fernando d'Ávalos, and behind them were blocks of Spanish
pikemen and German
landsknechts under
Georg Frundsberg. The Imperial
artillery, placed on several platforms jutting forward from the earthworks, was able to sweep the fields north of the park as well as parts of the sunken road itself. Most of the Imperial cavalry was placed at the south end of the park, far behind the infantry; a separate force of cavalry was positioned to the south, guarding the bridge. On the evening of 26 April, Lautrec sent a force under the Sieur de Pontdormy to reconnoiter the Imperial positions. Colonna, having observed the French presence, sent messengers to Milan to request reinforcements; Sforza arrived the next morning with 6,400 additional troops, joining the cavalry near the bridge to the south of Colonna's camp. At dawn on 27 April, Lautrec began his attack, sending the
Black Bands to push aside the Spanish
pickets and clear the ground before the Imperial positions. The French advance was headed by two columns of Swiss, each comprising about 4,000 to 7,000 men, accompanied by some artillery; this party was to assault the entrenched front of the Imperial camp directly. Lescun, meanwhile, led a body of cavalry south along the Milan road, intending to flank the camp and strike at the bridge to the rear. The remainder of the French army, including the French infantry, the bulk of the heavy cavalry, and the remnants of the Swiss, formed up in a broad line some distance behind the two Swiss columns; behind this was a third line, composed of the Venetian forces under
Francesco Maria della Rovere, the Duke of Urbino.
The Swiss attack The overall command of the Swiss assault was given to
Anne de Montmorency. As the Swiss columns advanced towards the park, he ordered them to pause and wait for the French artillery to bombard the Imperial defences, but the Swiss refused to obey. Perhaps the Swiss captains doubted that the artillery would have any effect on the earthworks; historian
Charles Oman suggests that it is more likely they were "inspired by blind pugnacity and self-confidence". In any case, the Swiss moved rapidly towards Colonna's position, leaving the artillery behind; there was apparently some rivalry between the two columns, as one, commanded by
Arnold Winkelried of Unterwalden, was composed of men from the rural cantons, while the other, under Albert von Stein, consisted of the contingents from
Bern and the urban cantons. The advancing Swiss quickly came into range of the Imperial artillery; unable to take cover on the level fields, they began to take substantial casualties, and as many as a thousand Swiss may have been killed by the time the columns reached the Imperial lines. , painted by
Jean Clouet (). Montmorency commanded the Swiss assault, and was the only survivor among the French nobles who accompanied it. The Swiss came to a sudden halt as the columns reached the sunken road in front of the park; the depth of the road and the height of the rampart behind it—together higher than the length of the Swiss pikes—effectively blocked their advance. Moving down into the road, the Swiss suffered massive casualties from the fire of d'Avalos's arquebusiers. Sources also imply d'Ávalos arranged his arquebusiers in multiple, successive ranks that would fire and file away to reload while leaving space for the next rank to fire, a novel technique at the time called
volley fire. Nevertheless, the Swiss made a series of desperate attempts to breach the Imperial line; some managed to reach the top of the rampart, only to be met by the landsknechts, who had come up from behind the arquebusiers. One of the Swiss captains was apparently killed by Frundsberg in single combat; and the Swiss, unable to form up atop the earthworks, were pushed back down into the sunken road. After attempting to move forward for about half an hour, the remnants of the Swiss columns retreated back towards the main French line Their total losses numbered more than 3,000, and included Winkelried, von Stein, and twenty other captains; of the French nobles who had accompanied them, only Montmorency survived.
Denouement Lescun, with about 400 heavy cavalry under his command, had meanwhile reached the bridge south of the park and fought his way across it and into the Imperial camp beyond. Colonna responded by detaching some cavalry under
Antonio de Leyva to halt the French advance, while Sforza came up the road towards the bridge, aiming to surround Lescun. Pontdormy held off the Milanese, allowing Lescun to extricate himself from the camp; the French cavalry then retraced its path and rejoined the main body of the army. Despite the urging of d'Avalos and several other Imperial commanders, Colonna refused to order a general attack on the French, pointing out that much of Lautrec's army—including his cavalry—was still intact. Colonna suggested that the French were already beaten, and would soon withdraw; this assessment was shared by Frundsberg. Nevertheless, some small groups of Spanish arquebusiers and light cavalry attempted to pursue the withdrawing Swiss, only to be beaten back by the Black Bands, which were covering the removal of the French artillery from the field. Colonna's judgement proved to be accurate; the Swiss were unwilling to make another assault, and marched for home on 30 April. Lautrec, believing that his resulting weakness in infantry made a further campaign impossible, retreated to the east, crossing the Adda into Venetian territory at
Trezzo. Having reached Cremona, Lautrec departed for France, leaving Lescun in command of the remnants of the French army. == Aftermath ==