1775
American Revolutionary War begins
Mars conjunct Uranus in Gemini coincided with the opening shots of the American Revolution — the Battles of Lexington and Concord. The United States was effectively born under this signature, which is why its natal chart carries Mars and Uranus conjunct in Gemini in the 7th house.

1861
American Civil War begins
On April 12, 1861 — with Mars conjunct Uranus in the sky — Confederate batteries opened fire on Fort Sumter and the Civil War began. The most violent internal rupture in American history was ignited under this exact aspect.
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1945
Atomic bombings and end of World War II
Mars moved into conjunction with Uranus in August 1945, reaching peak power on August 17 — the days surrounding the atomic bombings of Hiroshima and Nagasaki and Japan's subsequent surrender. The most destructive single military acts in human history occurred under Mars-Uranus. The conjunction was in Gemini's neighbouring signs but at the transition point.