The claimef violations of self evident "truths" in the declaration of independence include the right to commit genocide of the native population:

" He has excited domestic insurrections amongst us, and has endeavoured to bring on the inhabitants of our frontiers, the merciless Indian Savages, whose known rule of warfare, is an undistinguished destruction of all ages, sexes and conditions."

Britain wasn't allowing the colonies to expand westward, and the Patriots were pissed.