Passage: In England, Macduff is informed by Ross that his "castle is surprised; wife and babes / Savagely slaughter'd" (IV.iii.204–05). When this news of his family's execution reaches him, Macduff is stricken with grief and vows revenge. Prince Malcolm, Duncan's son, has succeeded in raising an army in England, and Macduff joins him as he rides to Scotland to challenge Macbeth's forces. The invasion has the support of the Scottish nobles, who are appalled and frightened by Macbeth's tyrannical and murderous behaviour. Malcolm leads an army, along with Macduff and Englishmen Siward (the Elder), the Earl of Northumberland, against Dunsinane Castle. While encamped in Birnam Wood, the soldiers are ordered to cut down and carry tree limbs to camouflage their numbers.

Question: Led by Malcolm, what did a coalition of armies march against?
Dunsinane Castle