What did freedom and difficulty have to do with the coming of the pilgrims in the poem "Landing of the Pilgrim Fathers in New England"?

The breaking waves dash'd high

On a stern and rock-bound coast,

And the woods against a stormy sky

Their giant branches toss'd.

And the heavy night hung dark 5

The hills and waters o'er,

When a band of exiles moor'd their bark* *small ship

On the wild New England shore

Explanation: hope this helps