Continuing then with the standard set by Steampunk, the prefix of 'diesel' in Dieselpunk is a euphemism for the culture, history, aesthetics and tropes of the time after the end of the Steam Era when internal combustion replace steam tech as the dominant technology. This post-Steam time period is often referred to in the Dieselpunk community as the 'Diesel Era' (Not to be confused with the respective eras in the locomotive tech.)
I don’t believe that there’s a hard line dividing the Steam Era and the Diesel Era. I believe that the Steam Era died a slow death in the blood and filth of the Great War. Then, like the mythological Phoenix, the Diesel Era arose from that same firestorm that consumed the Steam Era.
|World War 1 Dieselpunk|
|World War 2 or Possibly Korean War Dieselpunk|