Has Germany ever been attacked without attacking someone else first?
Depends on the time period under discussion. Going back to the early modern period, France has invaded Germany far more often than the reverse. France was the first of the major European states to achieve unification in something approximating its modern form, and the French threw their weight around for several hundred years. German unification came very late, but it changed the game; the simple fact is, there are a lot of German speaking people in the middle of Europe, they tend to work hard, and they tend to be competent. Everything else being equal, Germany is going to dominate Europe naturally. Germany doesn’t need a war to do this.