On the Fact that the Byzantines Regained Sections of Italy and Sicily In 540 (Through a War with the Ostrogoths) and Held On to it Most of it for Over Five Centuries

I never knew that until recently (or if I did know it I'd completely forgotten it). I had just assumed that when the West had fallen in 476 (the descent had actually started much earlier - the freezing over of the Rhine in 405, for example - but being that this is the date most typically used, I'll go along) all of Italy was gone forever. Of course it could have ended up even better (in terms of reclaiming more of the Western half) for the Byzantines had they not had to fend off the Muslims for 800 years but, still, quite impressive winning that Gothic War and at least getting some of their shit back.