Are there factors outside of time and damage taken that affect merit in Commandos:Behind Enemy Lines?

Solution 1:

Wrong, 3 silver stars for sustaining damage and 3 silver stars for mission time equals 3 gold stars and that's the maximum amount of merit per mission. You need 6 gold stars to get promoted. You need all 120 silver stars which equal 60 gold stars to get the maximum rank of Field Marshall. You need 30 gold stars to access the secret mission (that's the 20th mission, though in some versions of the game there's no merit requirement).

In my opinion, the time limit for 3 silver stars is more than fair.

However, you can basically abuse the system for merit by retrying missions, from end screen, so Field Marshall is probably attainable by retrying the first mission over and over. Seeing as how it can be done in one minute (you don't need the driver) you can realistically get to the rank of Field Marshall in less than half an hour...

Solution 2:

Further experimenting has yielded that merit is based only on time and sustained damage. Alas, the speed required to get three stars on "mission time" is significantly lower than what is required to get promoted, and if a player isn't getting full merit, they should keep retrying and going for better times, despite the end screen rating them with three stars.