Sniper Elite lets you have the freedom of how you want to do it. So you can run through the mission like Rambo, or stand in the back and take out one enemy after another with your sniper rifle, or, as this video show you, you can play as a stealth sniper and sneak through the mission unseen, taking out only the enemies that are absolutely necessary for the three main objectives (3 Snipers / Tank / General)
I decided to use non-lethal on the enemies which you have not to kill. You can also use lethal of course, it makes no noticeable difference. Also, you can save and reload at absolutely any time. Of course, this makes things extremely easy for you. In my video, however, I did not use a game save. It's a complete run from the beginning to the end and I finish the mission in ca 13 minutes.
One more important thingIf you want to replay this walkthrough, you need to know one thing. The enemies are in their fixed areas, but in this area they act completely "randomly". Each time you start the mission, the game decides to put the enemy in position A / B / C etc and let him run / interact routine A / B / C etc. This is great for replaying the game, but of course rather not good for a walkthrough. So you have to improvise a lot and see what your enemies are doing in their areas and how they stand to the other enemies. Fortunately, you can save at any time. When you are happy with a kill or section of the map, save. If not, reload the old save and try again.