I was perusing the history shelves of the Waterstones in Cardiff the other day and was struck by the composition of the section on German history. Now the Germans emerge into the written historical record at least by 102 BCE, when Gaius Marius defeated two German tribes at the Battle of Aquae Sextiae. In 9 CE "Hermann the German" defeated another Roman army at the Battle of Teutoberg Forest. The Germans, of course, took over Western Europe as the Western Roman Empire collapsed in the 5th century CE. (Westerncentrism note: The Roman Empire lived on until 1453 in Constantinople, the residents of whom, right until the end, addressed each other as "Romanii.") Germans have been a leading factor in most of European history since then.
As far as I could tell from the contents of the shelves of Waterstones, through those 21 centuries of German history, the Germans were fighting in World War II during about 95% of that period.