How about this. The Leader gives a mission to a squad (eg. kill those guys, get to that place, hold the line) and a corresponding bonus (either to Skill, Move or Armor). That bonus remains with them until they have succeeded, failed, or been wiped out. Until then, the Leader cannot give any more missions.
Success occurs when the squad completes its mission (they kill all the guys, they get to the place). They lose their bonus, and the Leader can give a new mission next turn. Some missions (hold the line) have no obvious way of being completed, so they can only end when the mission fails or the squad is wiped out.
Failure can occur at the end of any turn in which the squad did not complete its mission (as in, they did not kill all the guys, they did not get to the place, someone died). The controlling player can choose to voluntarily declare the mission failed, or any one opponent can try to win a What I Say Goes roll to have the mission fail. If the mission fails, the Leader blames one squad member, who is executed/thrown under a bus. The squad loses its bonus and the Leader can give a new mission next turn.
If the whole squad is wiped out before they succeed or fail, they have died gloriously for the cause. The Leader is a tactical genius and can give a new mission next turn.
Missions must be well defined; the success and failure conditions should be known to all players. They should also be specific; "kill those guys" isn't just a mission to kill any enemies, it's a mission to kill a specific squad or unit type. With "Get to that place" the place shouldn't be any spot on the table, it should be a particular terrain feature.