There are certain situational modifiers for combat and morale in Black Powder Wars.
+1 for hight advantage. This is for shooting or close combat.
+1 firing at close (canister) range.
+1 attacking a flank
-2 for firing at long range. Infantry firing with ranged combat always fire at long range.
+1 Defending works or in cover
+1 defending heights
+2 defending fortifications
+1 Commander is attached
-1 Out of command radius of a commander
-2 Being attacked from the flank or rear
Remember, failure of a morale check by 1 or 2 results in 1 step loss of morale (ie good order to disorder or disorder to route). A morale check missed by 3 or more results in a two step loss in morale.