Napoleon
On 1 April, Alexander addressed the Sénat conservateur. Long docile to Napoleon, under Talleyrand's prodding it had turned against him. Alexander told the Sénat that the Allies were fighting against Napoleon, not France, and they were prepared to offer honorable peace terms if Napoleon were removed from power. The next day, the Sénat passed the Acte de déchéance de l'Empereur ("Emperor's Demise Act"), which declared Napoleon deposed. Napoleon had advanced as far as Fontainebleau when he learned that Paris was lost. When Napoleon proposed the army march on the capital, his senior officers and marshals mutinied. On 4 April, led by Ney, they confronted Napoleon. Napoleon asserted the army would follow him, and Ney replied the army would follow its generals. While the ordinary soldiers and regimental officers wanted to fight on, without any senior officers or marshals any prospective invasion of Paris would have been impossible. Bowing to the inevitable, on 4 April Napoleon abdicated in favour of his son, with Marie-Louise as regent. However, the Allies refused to accept this under prodding from Alexander, who feared that Napoleon might find an excuse to retake the throne. Napoleon was then forced to announce his unconditional abdication only two days later.

Q: On what date did Alexander speak to the Sénat conservateur?
1 April