Using these lines from Act I and Act V, explain why it was important for Shakespeare to introduce the play with the account of Macbeth's performance in the battle against Macdonwald.

ACT I, Scene II

But all's too weak;
For brave Macbeth,—well he deserves that name,—
Disdaining fortune, with his brandish'd steel,
Which smok'd with bloody execution,
Like valor's minion,Carv'd out his passage
Till he fac'd the slave;
And ne'er shook hands, nor bade farewell to him

ACT V, Scene VII

What's more to do,
Which would be planted newly with the time,—
As calling home our exil'd friends abroad,
That fled the snares of watchful tyranny;
Producing forth the cruel ministers
Of this dead butcher, and his fiend-like queen,—
Who, as 'tis thought, by self and violent hands
Took off her life;