Born as the son of a royal bailiff at Damvillers, in Lorraine, Gérard joined a battalion of volunteers in 1791, and served in the campaigns of 1792–1793 under Generals Charles François Dumouriez and Jean-Baptiste Jourdan.

In the summer of 1794, Gérard joined the 71st demi-brigade and fought at the Battle of Fleurus and then at the capture of Charleroi and Aldenhoven where he rushed through enemy lines to establish a rope across the river to allow the troops to cross the Roer.

[1] As the Grande Armée marched to war in 1805, Gérard served as first aide-de-camp to Bernadotte and greatly distinguished himself at the battle of Austerlitz where he charged at the head of the French squadrons against the Russian Imperial Guard and was wounded by grapeshot to the thigh.

When the War of the Fifth Coalition broke out, Gérard was given command of the Saxon cavalry in Bernadotte's IX Corps and was so praised for his gallant conduct in the battle of Wagram that he was created a baron of the First French Empire.

Gérard continued to serve with Macdonald during his independent operations, at Goldberg he repeated what he had done at Bautzen, ignoring orders to retreat and launching an assault that put the enemy to rout.

During the final phase of the campaign, Gérard continued to distinguish himself, winning at the bridge of Guillotière, putting himself in the thick of the action at a skirmish around Vendeuvre and fighting with his corps at Saint-Dizier.

In this capacity Gérard took a brilliant part in the battle of Ligny, and on the morning of 18 June he was foremost in advising Marshal Grouchy to march to the sound of the guns to aid the emperor at Waterloo.

[1] Serving as a voice of moderation in the midst of political chaos, Gérard played an active role during the July Revolution of 1830, after which he was appointed minister of war and named a Marshal of France.

In 1836 he was named grand chancellor of the Legion of Honour in succession to Marshal Mortier, and in 1838 commander of the National Guards of the Seine département, an office which he held until 1842.