The First Continental Congress, a brazen show of both defiance and union by the American colonies on the road to revolution, met on this day in history, Sept. 5, 1774. 

It was the first time many of the transformative figures in human history known as the Founding Fathers would meet. 

John Adams, Samuel Adams, Patrick Henry, John Jay and George Washington all attended the convention at Carpenters' Hall in Philadelphia. 

The gathering of colonial leaders was sparked by the increasingly dire battle — a pressure cooker of punishments and protests — that was brewing between Parliament and the city of Boston.

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"Across North America, colonists rose in solidarity with the people of Massachusetts," notes the library of George Washington's Mount Vernon on the origins about the Continental Congress.

The convention came in the wake of the Boston Tea Party of December 1773. Colonists responded to a new round of parliamentary taxes by dumping shipments of British tea into Boston Harbor. 

Parliament doubled down with the Intolerable Acts of May 1774. 

They closed the port of Boston to trade, revoked the Massachusetts charter and severely restricted meetings of local government, among other affronts to a colony that had grown used to self-rule over the previous 150-plus years. 

Colonial leaders were stunned by the Intolerable Acts. They realized that Britain's unchecked power to financially and politically punish Massachusetts, which had no representation in Parliament, could soon strike them. 

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They demanded a unified colonial response.

"Goods arrived in Massachusetts from as far south as Georgia, and by late spring 1774, nine of the colonies called for a continental congress. Virginia’s Committee of Correspondence is largely credited with originating the invitation," states Mount Vernon. 

The convention was seen across New England, and in Massachusetts especially, as a rousing assertion of American autonomy in the face of growing animosity with Great Britain.

"There had been a rousing send-off in Boston, on August 10, 1774, and in full view of British troops," the late David McCullough wrote of the Massachusetts delegation's departure for the convention in his 2001 "John Adams" biography.

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"It had been a triumphal, leisurely journey of nearly three weeks, with welcoming parties riding out to greet them at town after town. They were feted and toasted, prayers were said, church bells rang," MuCullough also wrote.

"At New Haven, ‘every bell was clanging,' people were crowded in doors and windows 'as if to see a coronation.'"

The First Continental Congress consisted of 56 delegates from 12 of the 13 original colonies — Georgia did not participate. It lasted through October 26. 

The delegates were divided on a plan of response to intolerable British policies.

"Some preferred more defensive and potentially violent courses of action, such as the Suffolk Resolves, while others believed in peaceful protest like the Declaration of Rights," writes the Boston Tea Party Ships & Museum. 

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"Despite these difficulties, the delegates overcame such obstacles and produced several highly significant results of the First Continental Congress."

The most daring decision made by the Continental Congress was to adopt the Suffolk Resolves, which were written in Boston, on September 17. 

Among other actions, the Resolves called for Massachusetts to boycott British goods, renounce allegiance to the crown and stockpile military supplies. 

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"This was one of the happiest days of my life," John Adams wrote in his diary. 

"This day convinced me that America will support Massachusetts or perish with her."

British Redcoats marched from Boston on Lexington and Concord on April 19, 1775, in an effort to seize that colonial cache of weapons. 

They were met by Massachusetts Minutemen on Lexington Green and a bloody gunfight ensued. 

The American Revolution had begun. 

A Second Continental Congress was held in 1776 with the war underway.

That second convention would, on July 4, 1776, publicly sever America's allegiance once and for all to Great Britain.