Thank you OPstrator!
I had the same problem, where railroad lines, unit circles etc. wasn't visible.
dgVoodoo2 works, but I had to use v2.55.1 (the newest version was automatically deleted by Windows 10 as it says it contains a virus, so be a bit careful). I also used the D3DCompiler_47 and D3DRM.dll.
EDIT: Ironically though, now the introduction videos aren't working, only the text and sound. But that's a far lesser problem!
There is better solution using ReShade
Go to this page, https://reshade.me
Download Software, dont run it, before download file called "d3d8.dll" and put in a game directory https://github.com/crosire/d3d8to9/releases
After that run ReShade and show location of "Soldiers.exe" file, Programm will say what you need "d3d8to9" you press ok and after you will see down from big button will be 3 different variation of DirectX
You choose middle one, after that programm will ask do you like to download Assets you press ok and wait, after that you will see list with different assets, you just press ok and thats all.
Clouse ReShade and run game, you will have Text Sound, Rails and even green circles around your charecters!