Imagine for a moment being pinned down with your squad in a small lets say foxhole. Each of you has ran out of water in your primarys and your sidearms can't shoot the range of which your enemy is located. What do you do? You call a support squad.
Remember this always,
"If the average Army squad can never survive on its own than neither can a soaking squad"-XP270
So think If you need backup don't YELL "Shite, were pinned down get your arses over here NOW!" Just say "This is Sqaud 1 assaulting enemy's left flank, we need a support squad, over" Remember "These brave men leave thier duty to back you up, be grateful for that." -XP270