The Six Hundred Years War
1337 - 1945
It's a pet hunch of mine -- nothing like a 'theory' -- that all wars fought on European soil in the last six centuries are aftershocks, so to speak, of the Hundred Years War. My hunch was reinforced after reading Barbara Tuchman's A Distant Mirror.
Note also that the Wiki traces causes back to the Norman invasion of England. Oh, and I'm forgetting the post-Soviet deconstruction of the Balkan states... including Kosovo, that's (2008 - 1066) = 942 years, and counting.