stand to (attention)
1. To be or become ready for an attack. We were all told to stand to after receiving word that the enemy was preparing to launch an offensive just before dawn.
2. To quickly assume military attention. You become trained to stand to attention when a superior officer enters the room. I quickly stood to, but the general told me to be at ease.
stand to
v. To take up positions for military action: Upon hearing gunfire, the soldiers stood to.