Call of Duty 4 Walkthrough - All Ghillied Up
This seems to be a pretty polarizing mission for fans, as those that don't like stealth usually end up hating it. While going loud doesn't end the mission, it will make things harder and in certain situations definitely get you killed.
Follow MacMillian to the shed and take out the enemy soldier. You'll want to be prone for a large portion of this mission. MacMillian will guide you through this mission, so he might repeat a thing or two that I say in here.
After moving forward a little, you'll come to a church. Take out the guard up in the tower before taking out the two on the ground. After moving through the church, go prone in the dark grass and stay still as the helicopter hovers above. If it happens to see you, grab the stingers out of the church and take it out.
This next part seems a lot scarier than it actually is. A host of Russian soldiers will move through the field in front of them and if any of them see you, there's no way you and MacMillian can survive. However, if you follow MacMillian, stay down, and don't move, you should be fine. Even if soldiers get alarmingly close to you, you can remain hidden by remaining still.
When you get to the next area, taking out the two moving guards, but don't open fire on the two disposing bodies. Wait until your partner tells you to and then take out one as he takes out the other. Move forward into the container yard.
You should come across a suppressed P90, which is much better than your handgun. MacMillian will tell you to stay put, but kill the guard that walks into the open container. There are three guards huddled in close together, but you can easily sneak past them. If you're going for the laptop, you'll have to take them out.
For this next part, stick closely to your partner. Run out of the containers after him and go prone under the truck as quickly as possible. He'll take you under the trucks and to some more containers. This area is swarming with soldiers, so follow him closely the entire time.
Take out the sniper on the fire escape and follow your partner through the buildings. You'll come across a lone dog, but leave him along, or else you'll face a large pack of wild dogs, which can be incredibly hard to kill. There are no enemies for the rest of the level, so just keep advancing until it's over.