Under arms describes a state of military readiness (actual or ceremonial). Typically, troops are considered "under arms" when they are in uniform, on duty, and carrying a weapon (rifle, side-arm, or sword), as opposed to being in uniform, on duty, but not carrying a weapon.
Soldiers not actually carrying a weapon but wearing a service belt or web gear associated with carrying weapons may be considered to be symbolically "under arms".
Soldiers normally remove headgear while indoors; however, soldiers who are under arms normally wear their headgear indoors, with a few exceptions.
I know a place where I can go when I'm alone
Into your arms, whoa, into your arms I can go
I know a place that's safe and warm from the crowd
Into your arms, whoa, into your arms I can go
And if I should fall
I know I won't be alone
Be alone anymore
I know a place where I can go when I'm alone
Into your arms, whoa, into your arms I can go
I know a place that's safe and warm from the crowd
Into your arms, whoa, into your arms I can go
So if I should fall
I know I won't be alone
Be alone anymore
I know a place where I can go when I'm alone
Into your arms, whoa, into your arms I can go