Which country was the first to declare war in the conflict that would become World War I?

Austria-Hungary

Explanation:

On July 28, 1914, one month to the day after Archduke Franz Ferdinand of Austria and his wife were killed by a Serbian nationalist in Sarajevo, Austria-Hungary declares war on Serbia, effectively beginning the First World War.

Austria-Hungary

Explanation:

Austria-Hungary declared war on Serbia in 1914 after Archduke Franz Ferdinand of Austria and his wife were both killed by a Serbian nationalist.

hope this helps :)

. political or economical policy that isolates a country from participating in international relationships. it has been suggested that the united states participates in isolationism because of its lack of involvement in particular wars or alliances.