1. Delaware Statehood Day: December 22 is deemed as the Statehood Day of Delaware because it is the anniversary of when Delaware became the first state to join the Union in 1787.

2. First Major Battle of the American Revolution: On December 22, 1775, at the Iron Works Hill in New Castle, Delaware, American naval forces executed a critical attack against the British battleship Defender.

3. Delaware’s Ratification of the United States Constitution: Delaware was the first state to ratify the Constitution of the United States on December 22, 1787. This act marked a significant historical moment for the country's democracy and governance system.

4. The Bicentennial of the Delaware Constitution: The 150th anniversary of the Delaware Constitution was celebrated on December 22, 1892, with a grand ceremony in Dover, Delaware, attended by dignitaries from all over the United States.

5. New Jersey and Delaware Boundary Convention: On December 22, 1934, the Boundary Convention was held between Delaware and New Jersey to determine the exact location of the state border. The final decision in 1936 established the current boundary between the two states.