Are the battles in Macbeth good examples to explore the theme of violence and masculinity?

I would definitely want to argue that this is the case. I
think one of the best parts of the play you can use to argue this is actually at the
beginning of the play, in Act I scene 2, when Duncan is hearing the report of the battle
between the forces of Norway and the treacherous Thane of Cawdor. Note how the exploits
of Macbeth, who is called "Bellona's bridegroom," are
conveyed:

For
brave Macbeth (well he deserves that name),

Disdaining
Fortune, with his brandish'd steel,

Which smok'd with
bloody execution,

Like Valour's minion, carv'd out his
passage,

Till he fac'd the
slave;

Which ne'er shook hands., nor bade farewell to
him,

Till he unseam'd him from the nave to
th'chops,

And fix'd his head upon our
battlements.

What is
important to realise is that we have not actually been introduced to Macbeth yet. This,
then, is our first introduction to his character. And note what a bloody, violent
character he is presented as being. His blade smokes with "bloody execution" and he is
reported to have violently and perhaps excessively killed the Thane of Cawdor, chopping
him in two and beheading him. Yet note Duncan's response to this violent
deed:

O
valiant cousin! worthy
gentleman!

It appears that
from the beginning of the play such acts of gratuitous and aggressive violence are
linked with an approved sense of masculinity. To be a "man" who is worthy of preferment
and the King's notice, it is suggested, you have to be willing to perpetrate such acts
of violence.