The Third Legislative Assembly of the Wisconsin Territory convened from December 7, 1840, to February 19, 1841, and from December 6, 1841, to February 19, 1842, in regular session.^[1][2][3]

• January 26, 1841: The United Kingdom of Great Britain and Ireland took control of Hong Kong.
• February 10, 1841: The Act of Union was proclaimed in Montreal, establishing the Province of Canada.
• March 4, 1841: Inauguration of William Henry Harrison as the 9th President of the United States.
• March 9, 1841: The Supreme Court of the United States ruled in United States v. The Amistad that the Africans who seized control of the ship had been taken into slavery illegally.
• April 4, 1841: President William Henry Harrison died of pneumonia.
• April 6, 1841: Inauguration of John Tyler as the 10th President of the United States.
• August 16, 1841: President John Tyler vetoed the bill which would have established the Second Bank of the United States. Enraged Whigs rioted outside the White House.
• December 20, 1841: The Treaty for the Suppression of the African Slave Trade was signed in London by representatives of Austria, Britain, France, Prussia, and Russia.
• February 11, 1842: After a heated argument on the floor of the Council over the appointment of Enos S. Baker as Sheriff of Grant County, Councillor James Russell Vineyard shot and killed Councillor Charles C. P. Arndt.^[4] Vineyard subsequently attempted to resign from the Council—his resignation was refused and he was instead expelled.^[1]

• February 19, 1841: An Act to provide for the completion of the Capitol at Madison, 1841, Wisc. Terr. Act 37.^[2]
• February 18, 1842: Resolutions relative to the removal of Indians.^[3]

• 1st session: December 7, 1840 – February 19, 1841
• 2nd session: December 6, 1841 – February 19, 1842