National Unity Day in Hungary Date in the current year: June 4, 2024

National Unity Day commemorates the anniversary of the signing of the Treaty of Trianon. This peace treaty was signed between most of the Allies of World War I and the Kingdom of Hungary. The signing of the treaty officially ended World War I between them.

According to the treaty, the Kingdom of Hungary lost 72% of its territory and 64% of its population. Only about 30% of Hungarians were left in the post-Trianon Hungary. 10 largest cities of the kingdom were given to other countries. The treaty also limited Hungary's army to 35,000 officers and men, and the Hungarian Navy ceased to exist.

The signing of the treaty became a tragedy for Hungary. National mourning lasted until 1938, when Hungary started to expand its boundaries again. The Treaty of Trianon set the boundaries of Hungary, which are the same today. Only three villages were transferred to Czechoslovakia in 1947.