In a letter to his wife Abigail, John Adams predicted that "The Second Day of July 1776, will be the most memorable Epocha, in the History of America." Adams had good reason to make such a prediction, since July 2, 1776 was an extremely significant day.
On July 2, 1776, the Second Continental Congress voted to approve Virginia delegate Richard Henry Lee's motion for independence. Lee's motion had been put forward on June 7, 1776, after months of debate and over a year of armed conflict with the Mother Country. Lee's motion read:
"Resolved: That these United Colonies are, and of right ought to be, free and independent States, that they are absolved from all allegiance to the British Crown, and that all political connection between them and the State of Great Britain is, and ought to be, totally dissolved."
Thanks to some aggressive negotiations and politicking, John Adams and his supporters were able to get twelve of the thirteen colonies to vote in favor of Lee's motion. New York abstained.
This victory is what prompted Adams to write his wife, Abigail, the following:
"Yesterday the greatest Question was decided, which ever was debated in America, and a greater perhaps, never was or will be decided among Men. A Resolution was passed without one dissenting Colony 'that these united Colonies, are, and of right ought to be free and independent States, and as such, they have, and of Right ought to have full Power to make War, conclude Peace, establish Commerce, and to do all the other Acts and Things, which other States may rightfully do.'
"You will see in a few days a Declaration setting forth the Causes, which have impell'd Us to this mighty Revolution, and the Reasons which will justify it, in the Sight of God and Man. A Plan of Confederation will be taken up in a few days. On July 2, 1776 the Association known as United Colonies of America officially became the United States of America."
That "Declaration setting forth the Causes" would end up overshadowing the hardfought legislative victory of July 2. On July 4, Congress followed up its vote for independence with an approval of the Declaration of Independence. And it is that vote, which Americans have chosen to remember as their national birthday.