esprit de corps

noun1

1. •
   A shared spirit of comradeship, enthusiasm, and devotion to a cause among the members of a group, for example of a military unit.

   • “Well done, sister! I honour your esprit du corps^([sic]). When I am a wife, I mean to be just as staunch myself; and I wish my friends in general would be so too. It would save me many a heartache.” — 1814