[nine_k]

Possibly Balkans themselves were not important. The trade routes in Mediterranean likely were.

Also, there was a complex web of international treaties and alliances that eventually pulled the UK into the war.

[insane_dreamer]

This was back in the day when alliances, particularly European ones, meant something.

[nine_k]

Also, family ties. European monarchs were a really tight bunch. For instance, the tzar of Russia and the king of the British Empire at the time of WWI were brothers.

[sofixa]

> For instance, the tzar of Russia and the king of the British Empire at the time of WWI were brothers.

They were first cousins, along with the German Kaiser they went to war with.