Four years ago today saw the birth of one of America's hottest bands, One Direction. And this entire week has just been a 1D fan fest, with thousands of followers tweeting obsessively about the coming Anniversary.This morning, Niall Horan broke the internet when he tweeted a sweet, heartfelt thanks to his 1D cohorts."Thank you lads, we've had a great time so far, you are family to me now , not just band mates!Read more on NewsOK.com