Transferred to Spain, Boyer led a dragoon division at Salamanca and Battle of Venta del Pozo in 1812 and Vitoria in 1813.

Boyer was chief of staff in Jean-Andoche Junot's VIII Corps during Marshal André Masséna's invasion of Portugal in 1810.

[3] On 19 January 1814, Marshal Jean-de-Dieu Soult received the order to begin the transfer of the infantry divisions of Boyer and Jean François Leval to Napoleon's army operating near Paris.

[5] A detachment under Étienne Gauthier arrived in time to join Marshal Nicolas Oudinot's corps for the Battle of Mormant on 17 February.

[8] In the action, the French overran the village of Méry, but were unable to hold the part of the town on the north bank in the face of an Allied counterattack.

[12] The next day during the Battle of Craonne, Boyer's brigade operated with Marshal Michel Ney's Young Guard corps.

[13] That morning Ney prematurely launched the divisions of Boyer and Claude Marie Meunier against the Russian left flank.

When the French guns arrived, Meunier and Boyer's troops fought a costly battle with their enemies for several hours.