He fought under the great French knight Bertrand du Guesclin where he made his mark as a distinguished warrior. He was appointed the Constable of France by Charles VII in 1402.

With the changes taking place in the political climate in the French court of 1411, Charles was dismissed from his office. However, by 1413 his military service was once more needed and he was reappointed Constable.

In 1415 Charles served as co-commander of the French army along with Marshal Boucicaut. These two veteran warriors were unable to exercise control over the high-ranking nobility. Disorganized, the French forces went on to lose the Battle of Agincourt to English King Henry V's disciplined army. Charles I d'Albret was killed in the course of the battle.