Though the defenders were protected by field fortifications, a French frontal attack combined with a turning movement rapidly overran the position and routed the Neapolitans with heavy losses.

Following the decision by King Ferdinand IV of Naples to ally himself with the Austrian Empire, Russian Empire, and United Kingdom of Great Britain and Ireland and Napoleon's decisive victory over the Allies at the Battle of Austerlitz, Napoleon declared Bourbon rule of southern Italy at an end.

After the defeat, the Neapolitan army disintegrated away from desertion, and only a few thousand soldiers outlasted to be evacuated to Sicily by the British Royal Navy.

[1] For its part, the Austrian army in Italy under Archduke Charles, Duke of Teschen numbered 90,000 men.

Afraid that Saint-Cyr's corps might overrun his lands, the king concluded a treaty with Napoleon to remain neutral during the War of the Third Coalition.

[3] As soon as Saint-Cyr's army marched north, Ferdinand and Queen Maria Carolina violated the agreement and invited the British and Russians to land expeditionary forces in their kingdom.

This left Ferdinand alone to face the fury of Napoleon, who had determined to conquer the Kingdom of Naples and hand the crown to his brother Joseph Bonaparte.

[6] Saint-Cyr's corps was renamed the Army of Naples in January 1806 and placed under the command of Masséna, though Joseph was the nominal leader.

The 5,000 men of the left wing under General of Division Giuseppe Lechi massed at Ancona on the Adriatic Sea.

Its troops were poorly paid, clothed, and fed, leading the soldiers to rob the local people as a matter of course.

[7] French columns lunged across the border on 8 February 1806, finding no resistance and causing panic at the Neapolitan royal court.

Masséna's column quickly arrived before Gaeta, about 40 miles (64 km) north of Naples, where its commander Prince Louis of Hesse-Philippsthal refused a demand to surrender.

[6] Receiving word that the Neapolitan army was located to the south, Reynier left Naples and advanced[9] with about 10,000 troops.

Rosenheim, whose column was accompanied by Hereditary Prince Francis, withdrew in front of Lechi's division on the east coast while Damas fell back south of Naples.

[12] Reynier's scouts identified Damas' position on 8 March, and the French general prepared to attack the following day.

The pass behind the Neapolitans was the weakest point in Damas' defensive layout since it could make retreat difficult.

[12] The French general put one brigade in his front line, ordered his light infantry to turn the Neapolitan right flank, and placed Verdier in charge of the reserve.

[9] In a single file, Reynier's light infantry picked their way along the cliffs on Damas' right flank and ultimately emerged to the right and rear of their opponents.

At the same time, General of Brigade Louis Fursy Henri Compère led a frontal assault on the first line.

A French eyewitness, Paul Louis Courier, recorded that exhausted and starving soldiers robbed, raped, and murdered the inhabitants.

[18] During the retreat, the Neapolitan army dissolved; only 2,000 or 3,000 regulars from both wings remained to be taken off by ship to Messina in Sicily.

Plundering Imperial troops and grasping French civil authorities quickly set off a rebellion by the proud Calabrians.