Cook and Sunset shook their heads, and the younger mare added in an unsettled tone, "I remember Principal Celestia subbing in a history class once. She mentioned that armies around the time you talked about, um, Uncle Silver, had three branches—infantry, cavalry, and artillery. I didn't make the connection before, but Princess Celestia, in one of the last classes I had with her, talked about the three branches of the Guard, with the same names."