Answer:
To get ready for battle and by order of the noble court.
Step-by-step explanation:
Horatio says that according to rumours Fortinbras, the son of the last king (also called Fortinbras) who was defeated and killed by King Hamlet is now approaching Denmark with his army. This happens during the first act.
Horatio: "(...)His fell to Hamlet. Now, sir, young Fortinbras,
Of unimproved mettle hot and full,
Hath in the skirts of Norway here and there
Shark'd up a list of lawless resolutes,
For food and diet, to some enterprise
That hath a stomach in't; which is no other--
As it doth well appear unto our state--
But to recover of us, by strong hand
And terms compulsatory, those foresaid lands
So by his father lost: and this, I take it,
Is the main motive of our preparations,
The source of this our watch and the chief head
Of this post-haste and romage in the land."