I'm really trying to come up with something balanced:
1k, infantry. (3/3) 0op. Limited. British.
Blitz. Guard.
When destroyed, suppressed, or in frontline, become veteran instead.
Veteran:
(2/3) 3op.
Retreat at the start of your turn.
Essentially this is a cheap defensive infantry that will be defanged and start retreating back to your hand where it can be reused unless the enemy wants to try and kill it again. It can also be used aggressively to attack the attackers.
I think this would fit best with British guard and veteran synergy. (Oh and it could also synergize with retreat synergy if that still existed.)
Other cards:
USA:
2k, Bomber. (3-1) 2op.
Heavy armor 1.
Show on draw: Deal 1 damage to a random enemy unit in the frontline plus 1 for each bomber you control"
(Credit to JohnathanDJ.)