Page "Memoir '44" Paragraph 13

A unit does not necessarily have to be ordered, so when a player has 3 section cards that can move units on the left flank, but no units are present, he can play one, discard the card and draw another, however this consumes his turn.

Every turn, a maximum of one card can be played, except for the Ambush Tactic Card, which is played against an action by the other player.