Why were Canons important during the revolutionary war? What can you do with a cannon that you cannot do with a rifle or musket?
For one thing, cannons can shoot a very long way. Even during the Revolutionary War a cannon could shoot almost a mile.
For another, you can stuff a cannon with a whole bunch of round bullets and shoot them all at once. This was called grapeshot.
The British army had a lot of cannons, the colonial army didn't have very many. That is why the capture of Fort Ticonderoga early in the Revolution so important. It had a lot of cannons.