“Their Finest Hour,” a Tom Brokaw documentary in honor of host country Great Britain, will premiere on Saturday during NBC’s daytime coverage of the London Olympics which starts at 10amET/PT.

> Update: NBC’s now says “Their Finest Hour” will air during NBC’s primetime at 8pmET/PT.

“Their Finest Hour,” which was shot across Britain over the course of two years, explores the years leading up to America’s entry into World War II. In 1940 and 1941 Britain stood firm against Nazi terror. And, as historian Anthony Beevor recalls in the documentary, Hitler would have ruled all of Europe, and there would have been very little the United States could have done about it.

The documentary includes recently discovered color film footage of the period. Airing the day before the Closing Ceremony, NBC says “Their Finest Hour” is a tribute to England as the host of the 2012 Summer Olympics.