Benjamin Franklin helped make the rattlesnake a symbol of Americans' reluctance to quarrel but vigilance and resolve in defense of their rights.
"By 1775, when Gadsden presented his flag to the commander-in-chief of the Navy, the rattlesnake was a symbol of the colonies and of their need to unite in defense of threats to their God-given and inherited rights. The flag and the bumper sticker symbolize American patriotism, the need to defend Americans' rights, and resistance to tyranny's threats to American liberty.
Those threats included - and include - illegal taxation, profanation of Americans' rights, and violation of the fundamental principles of American law."