USA HISTORY

Detailed explanation-1: -Austria-Hungary made first declaration of war against Serbia because of assassination of the Austrian Prince Francis Ferdinand and his wife Sophia on June 28, 1914.

Detailed explanation-2: -On May 23, 1915, Italy declares war on Austria-Hungary, entering World War I on the side of the Allies-Britain, France and Russia.

Detailed explanation-3: -Telegram of Austria-Hungary‘s declaration of war on Serbia on 28th July 1914. Telegram of Austria-Hungary‘s declaration of war on Serbia on 28th July 1914 marked the beginning of the First World War – one of the world’s most tragic conflicts in the history of human race and initiated the era of unprecedented suffering.

Detailed explanation-4: -Austria-Hungary, with German encouragement, declared war on Serbia on 28 July. Russia’s support of Serbia brought France into the conflict. Germany declared war on Russia on 1 August and France on 3 August.