Op's comment was about how this is not a given. Though tbf I can't recall any "peaceful" dictatorships, while I can recall a few war-happy democracies.
In my own country, Spain, the Francoist dictatorship (1939–1975) never attacked other countries or participated in any foreign wars (beyond sending a division of volunteers to WWII). Its domestic policy was highly repressive with common execution of political dissidents, etc., but in the sense of "no war" it was peaceful. The same goes for Salazar's Portugal, Hoxha’s Albania or Tito's Yugoslavia.
Op's comment was about how this is not a given. Though tbf I can't recall any "peaceful" dictatorships, while I can recall a few war-happy democracies.