What's wrong with cheat codes? They're simpler and save time.

It's the fastest way, and you don't have to type anything. It's very convenient when you're trying to capture certain objects with a specific composition and number of troops.

Create a shortcut to the Heroes3.exe file and add /nwcgrail to the end of the file path, as shown in the first image.
Launch it from the shortcut, press F4, but make sure the color depth is 16-bit.

A menu will appear with options like infinite movement and instant victory, among other useful functions.