European colonization and expansion meant that wars could truly become global events now.  Nationalistic rivalry between Britain and France led to over 150 years of nearly non-stop war between 1650 and 1815.  Not only did the wars involve people who lived in the two nations, but it also involved native groups allied with those countries and colonial subjects.  These large-scale wars were not cheap to fight, so Britain and France had to improve their abilities to tax their subjects.  Britain lost its American colonies due to its inability to tax them fairly and the French monarchy was deposed due to its unfair tax burden on the peasantry.  

European colonization would also play a role in both world wars of the twentieth century as well.  Economic and nationalistic rivalries in Europe stemming from colonization helped to drive the tensions that created WWI.  In WWII Japan sought to end European colonization in Asia by making themselves the major regional power in Asia--this was one of the driving factors of WWII.  After WWII colonies in Asia and Africa sought their independence from their parent countries.  In many cases these newly formed countries such as North and South Vietnam would ally with one of the world's leading superpowers, the United States or the Soviet Union.  This would be part of the Cold War as America and the Soviet Union fought proxy wars in the developing world.  All of this was a continued legacy of European colonization.