What persuaded Henry to reject his mother’s advice and enlist in the army?

Henry dreamed of grand battles that "thrilled him with their sweep and fire," and he seems to desire a "Greeklike" or "Homeric" struggle.

One night, as he lay in bed, the winds had carried to him the clangoring of the church bell as some enthusiast jerked the rope frantically to tell the twisted news of a great battle. This voice of the people rejoicing in the night had made him shiver in a prolonged ecstasy of excitement. Later, he had gone down to his mother's room and had spoken thus: "Ma, I'm going to enlist."