The old general served as a fusilier in the French light infantry during his youth.

fusilier 是由 fusil（法语"燧发枪"）加后缀 -ier（表示"与...相关的人"）构成的名词，字面意思是"使用燧发枪的士兵"。在军事术语中特指18-19世纪装备燧发枪的轻步兵。