The primary opposing forces in the Hundred Years' War were England and France. This conflict, which spanned from 1337 to 1453, arose primarily over territorial disputes and claims to the French throne. It saw notable battles, including Crécy and Agincourt, where English forces, utilizing longbows and tactical innovations, achieved significant victories. Ultimately, the war was marked by shifts in power, with France eventually reclaiming territories and asserting its dominance. The Hundred Years' War also influenced national identity in both countries and led to changes in warfare, culminating in the rise of strong centralized monarchies.