Trial and execution
When Napoleon was defeated, dethroned, and exiled for the second time in the summer of 1815, Ney was arrested on 3 August 1815. Marshal Moncey was ordered to assume the presidency of a court-martial convened to try Ney but the marshal declined and was for a time imprisoned for it. The King's government then appointed Marshal Jourdan as president and when it finally convened on 9 November 1815, the court-martial comprised the marshals Jourdan, Masséna, Augereau, and Mortier, and the generals Gazan de La Peyriere (instead of Maison who refused), Claparède and Villatte. After long deliberation, the court-martial voted 5–2 to declare itself "non-competent".
After the court-martial decided on 11 and 12 November that it did not have jurisdiction, Ney was tried on 16 November for treason by the Chamber of Peers. Key evidence in the trial was supplied by Ney's subordinate commanders Generals Bourmont, an arch royalist, and General Lecourbe, a republican who had fallen out of favour during the empire and was now in service to the King. Bourmont testified that Ney had been a keen supporter of Napoleon and gave evidence such as the accusation that Ney was wearing an Imperial Eagle decoration minutes after his decision to switch sides, suggesting some element of planning. Ney responded with outrage:
Monsieur de Bourmont accuses me to clear his own conduct. It seems that he prepared his denunciation of me months ago at Lille witness in another place. He flattered himself perhaps that we would never meet again face to face. He thought I would have short shrift like Labedoyere. I have no oratorical talent, but I come direct to the fact. It is unfortunate for me that General Lecourbe is no longer living. But I call Him [pointing upwards with his right hand] against these depositions, I appeal to a higher tribunal, to God who hears us all, to God who —you and me, Monsieur de Bourmont!— will judge us.
No other witness corroborated Bourmont's claim that Ney had been wearing an Imperial eagle decoration. While Lecourbe had died, testimony he'd given to a magistrate was read at the trial, showing Lecourbe thought the royalist situation lost and that Napoleon's 14,000 men could not be practically resisted by the 5,000 men of dubious loyalty under Ney's command.
In order to save Ney's life, his lawyer André Dupin declared that Ney was now Prussian and could not be judged by a French court for treason, as Ney's hometown of Sarrelouis had been annexed by Prussia according to the Treaty of Paris of 1815. Ney ruined his lawyer's effort by interrupting him and stating: "Je suis Français et je resterai Français!" ("I am French and I will remain French!"). On 4 December, when the Peers were called to give their verdict, 137 voted for the death penalty and 17 for deportation; five abstained. Only a single vote, that of the Duc de Broglie, was for acquittal. On 6 December 1815, he was condemned.
On 7 December 1815, Ney was executed by firing squad in Paris, near the Luxembourg Gardens. He refused to wear a blindfold, stating: "Are you unaware that I've spent twenty-five years staring down at cannonballs and bullets?". He was allowed the right to give the order to fire, reportedly saying:
Soldiers, when I give the command to fire, fire straight at my heart. Wait for the order. It will be my last to you. I protest against my condemnation. I have fought a hundred battles for France, and not one against her ... Soldiers, fire!
Ney's body is buried in Paris at the Père Lachaise Cemetery.