Why did World War I becam a world war?

Answer 1

World War 1 became a world war basically from the beginning because both Britain and France brought their colonial troops to war with them. Indian, African, and Asian colonial forces fought in Europe and in their home countries against opposing forces. When the Ottoman Empire entered the war, all of the Middle East became involved and fighting ranged from Egypt to Iraq. Additionaly, Canadian, New Zealand, and Australian troops fought for Britain from the beginning of the war.