WWII Slovakia
Right hand traffic had already been introduced in Slovakia by a decree of the government of "autonomous Slovakia" within Czechoslovakia in late 1938. Buses in the capital Bratislava were adapted in 1939, and the last roads in Slovakia switched to the new system in 1940/1941.
The area which is now Southern Slovakia was occupied by Hungary then and so would not have changed until Hungary changed in 1941.
Read more about this topic: Switch To Right Hand Traffic In Czechoslovakia