How did westward expansion and the american desire for land played a role in the buildup to war against britain? i need this answer asap with 3-5 sentences.

When the united states were originally trying to move westward to accommodate for its growing population and the British feared that if they moved too far westward it would become too hard for the British to keep tabs on them. But being the US still wanting land they moved westward forcing the British to send their Military and push the colonist back east 
I hope this helps obviously change up the wording because i used United States where i should say colonist and this also isn't my best writing sorry