Answer:
The writer of Common Sense in 1776, who was also an advocate of America's separation from Great Britain, was Thomas Paine.
Explanation:
Thomas Paine was an Anglo-American philosopher, freethinker, and revolutionary. He played an important role in both the American and French Revolutions and is one of the most important thinkers of liberalism. He is known, among other things, as the author of the controversial and widely read pamphlet Common Sense that he wrote to defend the interests of American settlers in 1776.
After the American independence, Thomas Paine returned to Europe. He first went to England, from where he was expelled for publishing The Rights of Man. Then he went to France, where in the midst of Jacobin Terror, he was imprisoned by Robespierre for his opposition to the terrible measures which he claimed violated the principles of the revolution itself (for example, Paine openly condemned the execution of Louis XVI).
In 1802 he returned to America, invited by President Thomas Jefferson, but this return coincided with a bad time for his ideas, as it was a time of revival of religious movements, which opposed him in defending deism. In addition, their political ideas aroused opposition from the federalists.