The American revolution did not end in 1776. The war went on until 1789. 1776 was when we officially declared independence, but the revolution had just begun. The American troops were badly outnumbered, and ill equipped to do anything, especially fight a war. With the aid of France and some Native American tribes, we finally ended up fighting the British off.
We had to fight them again in 1812, again with a very ill equipped and un-experienced military. At the Mississippi delta, General Jackson fought off the British forces with a ragtag force composed of a handful of military troops, pirates, and local citizens. The British over-ran our capital, and forced President Madison out of the White House. When our own forces failed to keep the enemy at bay, Mother Nature, or God if you prefer, intervened and drove them out in the form of a massive tornado and electrical storm.
Here's a music video about Jacksons battle at the Mississippi delta:
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