Patrick Henry was trying to convince the delegates at the convention to go to war against the British.  He needed to evoke emotional responses of justified anger from them to win them over to his ideas.  The words he uses are like power kegs of secondary emotional meaning.  The American Heritage Dictionary says that

 "A connotation includes the emotions or associations that surround a word." (See Link)

Patrick Henry, an outstanding orator, was not naive to the power of words.  He creates feelings of loyalty with words such as patriotism, freedom, and liberty. He also uses words such as betrayed, treason, submission, retreat, disloyalty, subjugation, slavery, and death to stir up the righteous indignation of these  men. He utilizes powerful phrases in the speech such as insidious smile and illusions of hope, and the one phrase that will evoke emotion even today in speeches God and our country.