You guys need to read a little more history and watch a little less History Channel. It wasn't just the British Empire that contributed troops to the fight. As I said before, Russia and China suffered horrific casualties that we can't even begin to imagine (millions, in Russia's case it is sometimes estimated up to 20-25 million), while tying down the bulk of the Axis forces (the Japanese had over a million troops in China, a million less for us to face on the islands of the Pacific). They are not the only ones, most of the forces in Italy were not American. They had a division from Poland (those who had escaped the Nazi occupation), and one from Brazil to name a few. A lot of the Commando groups formed by Britian were from particular countries like Belgium, Norway and even France. The Free French provided vital troops to Montgomery's Eighth Army in North Africa, and were some of his best troops. Montgomery also defeated Rommel at El Alamein with no American troops in 1942, and although a lot of his equipment was American at that time most of it was designed and built in Britian. On the other side of the world, the Commonwealth provided over 20% of the ships off Okinawa duing the invasion there in 1945.
Don't forget the massive resistance movements in Europe. At their peak in 1944, they tied down hundreds of thousands, yes that many, of German troops that could have been fighting us at Normandy. France and Yugoslavia were the most notable examples of this.
Finally, American casualty rates were by far the lowest of any of the major allied powers in WWII. Our 300 odd thousand dead pale in comparison to Russia, China and even Britian. Britian had tens of thoiusands of civilian casulties from German bombing alone.
Thinking that the US took most of the casualties and won the war with a little British help is a disservice to all of those who fought against the Axis.