The Hundred Years' war, the Eighty Years' war, and the Thirty Years' war are the most long wars of European History, aren't they? No, they are not. There was the Seven Hundred Years' war!
However, would you be surprised, if you knew that there have never been neither the Hundred Years' war, nor the Eighty Years' war, nor the Thierty Years' war. These wars were nothing else than chains of military conflicts, which historians united by common definitions for ease. For instance, the Hundred Years' war just consisted of four separate wars took place during 116 years, and in some of which took a part spaniards, flemishes and germans. The Eighty Years' war consisted, at least, of two wars happened long during 82 years. Despite duration of the Thirty Years' war amount precisely 30 years, like the both ones mentioned above, this war also was not being the one event; it numbered four military campaigns.
The logic which is being using by historians to merge separate particular conflicts and campaigns into the one big war is the actions of all of the conflicts were served to reaching the one goal. Often, because of constantly delaying of the ending of the war, the essence of the war did might dramaticaly changed. So, the Thirty Years' war began as a religious war and catholics fought protastants. But in three dtcades it ended without any hint of religious conflict and french catholics thogether with protestants war on spanish and austro-german catholics and Habsburg family. However, these facts don't cancel the reason of Thirty Years' war - France and Habsburg Empire sought power over the Europe and couldn't share it between each other.
If historians could merge any conflicts into the one, using the logic, described above, why wouldn't we can the same way when we're studying European history? Let's DO THAT!
739 Years' Anglo-French War was full of dramatic turns. For example, 18 July 1429 AD happened the Battle of Patay, which turned the tide of war in favor of Frenchmen. And exactly 386 years later, 18 July 1815 AD cannon roar of the Battle of Waterloo thundered all over the Europe and brought the victory over Napoleon to Englishmen.
The confrontation between England and France takes its begining in 1066 AD, when Normans invaded into British Isles from the territory of Northern France. Since that time England wared on France every in 10-20 years. From 1066 to 1815 AD we can count 38 armed conflicts between England and France.
These wars might be merged by common logic - the two kingdoms fought for both domination and suvereignity, early in the region, and further in the whole world.