I can give you an outline.
Paragraph one (intro) talk about the colonied bdcore the war. Introduce the two sides. Include your thesis statement. Try to use three reasons the independance declaration began. But short.
Paragraph two. Talk about the first reason in detail.
Paragraph three talk about the second reason in detail.
Paragraph four talk about the thrid reason in detail.
Paragraph five (conclusion) wrap it up with how it ended and dont forget to restate your thesis!
Hope this helps a little bit!!!