In World War II, the "scorched earth" policy in retreat was first applied by the .....?

Now they are scorching Ukraine.

Actually a recycled tactic from when Napoleon tried the same thing.

Newt, not just Napoleonic. It has been a common strategy from ancient times. Deprive your invading enemy of food, resources. Pretty obvious. The local peasants suffer more though.

Newt, the question states ww2. in this case, Finland was the first. In 1939-40 in the winter war V Russia.

“…denying or destroying…”