Cozy mysteries set in the past have a double edged appeal for writers and readers. They conjure up a recent past and have all the best qualities of historical fiction plus a mystery.
Several excellent series are based around events of World War 1 or 2. The historical background gives more depth to the genre though readers who prefer the lighter touch may well choose tea shop mysteries instead.
Some of my favorites are…pause while I research exact titles…and have a little think.