At the beginning of the play, the enemies are Norway and traitors and rebels within Scotland itself. In Act 1, sc. 2, we hear of how Macbeth was victorious in battle against Norway, against the rebel Macdonwald, and against the traitor, the Thane of Cawdor. The Thane of Cawdor had aligned himself with Norway in trying to defeat Duncan's forces. By Act 5, Macbeth's enemies are most of the people of Scotland. Malcolm, having fled to England when his father was killed, has gathered English forces to back him in his efforts to unseat Macbeth. Macduff has joined with Malcolm in the attempt. In Act 4, sc. 3, Macduff tells Malcolm how bad things are in Scotland under Macbeth's rule. Most of Macbeth's Thanes have left him and he is nearly on his own by the end of the play.
As the bleeding sergeant reports in act1 sc.2, the two enemies that Duncan's Scotland had to face were 'the merciless Macdonwald', the rebel from the Western Isles, and the king of Norway who got the support of the traitorous Thane of Cawdor.
Macdonwald was cruel and villainous, and he enjoyed the illegitimate indulgence of Fortune until Macbeth appeared on the scene of battle. Macbeth 'unseam'd him from the nave to the chaps/And fix'd his head upon our battlements'.
Norway and Cawdor 'began a dismal conflict', and it was the noble and heroic Macbeth again who overcame the offensive.Clad in armour and proof against sword/spear, he confronted the enemies, 'Point against point rebellious, arm against arm' to register the victory of Scotland.
However, Macbeth usurped the throne of Scotland by killing the good old king, Duncan; he then embarked on a bloody career to go on killing people. Ironically though, the king of Scotland himself turned out to be the greatest enemy of Scotland. He was overcome by an English army led by Malcolm and Macduff. Macduff beheaded Macbeth, and that led to the coronation of Malcolm.