1. Download the patch for Cossacks Art of War from
http://www.gsc-game.com/index.php?t=downloads&ss=299&s=patch

2. Extract it
There is a file named ddraw.dll

3. Find your Local Files for Cossacks Art of War by Steam or its probably Steam/SteamApps/Common/Cossacks

4. Make a copy of mdraw.dll and delete it from this folder

5. Now copy ddraw.dll to the destination folder

6. Rename ddraw.dll to mdraw.dll

Probably after solving problem with black screen there will be a problem with colours

After solving problem with black screen there will be a problem with colours.

I've found some information in another forum:

1. Open text editor (notepad)

2. Copy and paste

taskkill /f /im explorer.exe
dmcr.exe
start explorer.exe

3. Next save the file by using "Save as", choose "all files" and save as Dmcr.bat

4. Copy the file Dmcr.bat to the main folder Cossacks Art of War.

5. Run the game using dmcr.bat which works as exe file now. You can make a shortcut on your desktop.

If it's not working try tu use Alt+Tab go to the desktop and use Alt+Tab again to go to the game again.