The American Revolution was principally
caused by colonial opposition to British attempts to impose greater control over the colonies and to make them repay the crown for its defense of them during the French and Indian War (1754–63)
Beginning after Columbus' discovery in 1492 the exchange lasted through the years of expansion and discovery.
If you can please Provide answer Choices but other than that, I would think at the end of WW2 we had issues cleaning up the Radiation of the bombing in Japan and dealing with how to help the Jews that were captured and kept in encampments.