- United Colonies April 19: The American Revolutionary War begins at Lexington-Concord. It is unknown who fired the first shot, however the birth of a new empire begins.
- United States July 4: After months of debate, the United States of America officially declares independence from Great Britain.
- Kingdom of France: The French officially enter the American Revolution in favor of the Patriots and to strike at Great Britain's power.
- Great Britain April 11: After seven years of fighting, the British surrender after the Battle of Yorktown.
- September 3: The Treaty of Paris officially ends the American Revolution. Great Britain is forced to recognize the sovereignty of the United States.
- United States: The Constitutional Convention offers Prince Henry of Prussia the position as King of the United States. Henry accepts the offer immediately.
- Prussia: Prince Henry promptly moves from Prussia to the United States to attend the Constitutional Convention.
- June 21: The Constitution of the United States is ratified, granting four equal branches of government.
- Prince Henry is crowned Henry I of the United States. The ceremony is attended by all United States officials including President John Hancock.
- August 3: King Henry dies in Washington D.C.. As he had no children, his brother, Augustus I, succeeds him as King.
- New France: The Franco-American War begins after the American ultimatum to cede New Orleans to the U.S. expires.
- May 2: King Augustus dies. His son, Augustus II, succeeds him as King.
- United States: The Protectorate of Liberia is established on the coast of West Africa, with its initial intent to send freedmen back to Africa. This is the first oversea colony established by the United States.
- Texas: The Republic of Texas joins the United States after being recognized as independent from Mexico.
- April 25: The Mexican-American War begins after numerous problems arose between the United States and Mexico.
- February 2: The Mexican-American War ends in favor of the Americans. The United States annexes the Californian Peninsula and all land to the north and west of Texas.
- United States/Confederate States April 12: The First American War begins between the United States and the Confederate States of America.
- Washington D.C., United States April 15: While attending a play with President Abraham Lincoln, King Edward I is shot and killed by famed actor John Wilkes Booth.
- United States May 9: After years of vigorous fighting, the United States re-annexes the Confederate States.
- Saint Petersburg, Russia: Following both the Crimean War and the Alaska Purchase, the United States and Russia enter a military alliance in case of war against the British, French or Ottomans.
- Germany January 17: After years of war and competition, the Prussians officially form the German Empire, absorbing all predominately German-speaking nations (excluding Austria, Switzerland, and Luxembourg)
- Frankfurt, Germany May 10: The Treaty of Frankfurt is signed, ending the Franco-Prussian War and ceding Alsace and Lorraine to the Germans.
- Germany: The Berlin Conference concludes with improvements in African colonialism. Portugal and the United States decide to make the colonies of Angola and Mozambique cooperated, with the United Kingdom and Portugal cooperating the land in between. Germany gains Kamerun, Zanzibar and Namibia.
- London, United Kingdom January 11: The London Agreement is settled between Portugal, the United Kingdom and the United States, dividing up Portuguese-African claims after the Angola Crisis. The Americans gain Angola and Mozambique while the British gain all land in between.
- New York City, United States June 10: The Quadruple Alliance is created as a way to combine the Russo-American Alliance, the German-American Alliance and the German-Italian Alliance to protect each other in case of a possible war with the French, British or Austrians.
- Paris, France: The Triple Entente is established to counter the Quadruple Alliance of Germany, the United States, Russia, and Italy.
- March 24 – After weeks of persuasion, President Theodore Roosevelt receives congressional approval and Henry IV's royal assent to declare war on Mexico in order to end the bothersome Mexican Revolution and Anglo-Mexican cooperation.
- Paris, France September 15: The Establishment Acts (later known as the Acts of 1931) pass, re-establishing the Bourbon monarchy, instating Alfonso XIII of Spain as Alphonse I and pronouncing Charles Maurras the head of government for life.
- Vienna, Austria January 30: Adolf Hitler is sworn in as Chancellor of Austria, marking the beginning of Nazi leadership in Austria, known as the Machtergreifung.
- London, United Kingdom June 7: Oswald Mosley begins his service as Prime Minister with the support of the British Union as well as conservative allies and even from Prince David, heir to the British throne.
- June 22 – Confederate forces under the command of General George S. Patton move across the Ohio River onto Evansville, Indiana, taking the city in relatively short order. On the same day, U.S. President Al Smith asks Congress to declare war on the Confederate States of America. The vote passes unanimously sans one Congressman.
- Crown Prince Robert is assassinated.
- May 28 - King Edward VIII dies, leaving his neice Elizabeth as Queen.
- King Henry IV dies, leaving his grandson Edward as King Edward II.