Why one founding father didn't want July 4 as America's birthday

This Fourth of July marks the nation's 240th birthday. In 1776, the Continental Congress officially adopted the Declaration of Independence, but one of the founding fathers and second president, John Adams, didn't think the Fourth was the right day to commemorate the start of our nation.

"Congress actually passed a resolution in favor of independence on the 2nd," historian Kenneth C. Davis said Monday on "CBS This Morning."

Adams went to write a letter to his wife, Abigail, saying, "The Second Day of July 1776, will be the most memorable Epocha, in the History of America."

"He was right about everything but the date, because two days later, the Congress adopted Jefferson's declaration, which explained the reasons why they had had the vote two days earlier," said Davis, author of "Don't Know Much About History." "But when American people saw the declaration with the date at the top, July 4, it instantly became recognized as the birthday."

To set the context, the nation was already at war in 1776.

"When these 56 men are sitting down, they are in open rebellion against the most powerful man on earth," Davis said. "We sometimes take that for granted -- that these men who say, 'We pledge our lives, our fortunes and our sacred honor' -- were really risking everything. They were politicians, but they were doing something very brave."

John Adams, by the way, didn't celebrate the Fourth of July.

"He stood his ground, but he was alone in that pretty much," Davis said, smiling.

Was it coincidence or "divine providence"? Watch the video above to learn which three presidents died on July 4.