1942 - June 5 – The United States declares war on Bulgaria, Hungary & Romania.

In 1942, during World War II, the United States declared war on Bulgaria, Hungary, and Romania due to their alliances with Nazi Germany and their involvement in the war. This declaration was part of the broader American effort to combat the Axis powers and support the Allied forces. The decision to declare war on these countries was influenced by their roles in supporting Germany's military efforts in Europe. Bulgaria, Hungary, and Romania were part of the Axis powers, which also included Germany, Italy, and Japan. The United States' declaration of war signaled its commitment to the Allied cause and its determination to defeat the Axis powers.