To be fair, the article does have the line "Four words that sparked the revolution and brought down an empire." I think this refers only to the Americans defeating the British in the revolution; that's how the British Empire/government was brought down, in this instance. But, of course, the British continued to have dominion in India, Canada, Australia, Africa, and elsewhere, well into the 20th Century. Perhaps time and multiple independence movements, etc. can be said to have brought down the British Empire, in terms of ultimately ending it.