Sniper Elite 4/Allagra Fortress

After the events of Giovi Fiorini, where the partisans were killed in an ambush, the allied team still got enough intelligence about the missiles. Karl is sent to Allagra to call in a bombing run, and to make sure that there's not much to salvage.

Entering the fortress
When the mission starts, head forward and climb up the two poles. You will be at the south-east corner of the fortress's entrance with a bunker ahead, a frozen river to the north and spanned by a bridge. The main entrance is covered by two turrets. There is also an artillery spotter, and a radio operator on patrol.

There are four other side entrances as well. If you're approaching the ones on the west, be careful of the mines that cover the western ascent. When you approach the north-west pillbox, you can either take the passage at the midway between the pillbox and main entrance, or defeat the three enemies in the bunker to take the western-most entrance.

If entering by the right, you will have to sneak or fight through a pillbox with two Jagers. Past the pillbox are three enemies, including one officer with a safe code. This route allows accessing the eastern cross-corridor and the missile area.

Optional: Intercept Course
The first optional objective is to retrieve the Nazi Missile Strategy. You will likely want the safe combination carried by the officer outside of the eastern entrances.

The save containing the strategy is located in the western-most room inside the fortress. It may be opened with the safe combination for additional rewards, or can be blasted open with a satchel charge for just the documents.

Optional: Mischief-Maker
There are five Razor missiles that are almost ready and should be disabled. All of them can be explosively sabotaged by shooting the tip of the missile, or a more discrete damage can be done by approaching the exposed side of the tip and interacting with the missile.

Two missiles are stored in the fortress's hangar, which is found in the eastern part of the fortress. Specifically, there one in each of the south-west and south-east corners. There are several Jagers in this area, and thus might require some combat to reach these missiles.

Rocket Science
The missile technical specification is useful. They're casually placed on the table in the control room overlooking the first two missiles.

Heart of Darkness
Karl needs a way to mark the fortress for the bombers, and the fuel processing facility will help. To start, there are three hydrogen peroxide valves that need to be fixed. The valves can be discretely turned, or can be shot for a noisy sabotage.

Two of the valves are found in the second cross-corridor. The first is at the western intersection, and the second at the end.

The third valve is located in the centrifuge room on the upper floor. Reaching it requires entering by going to the upper floor on the hangar.

Once all valves are turned or damaged, head to the north-west corner of the trainyard and activate the centrifuge. This will overload the machine, and create a smoke trail for the bombers.

Head to the radio room on the north of the trainyards. Before calling in the bombers, make sure your weapons are reloaded and that you are at full health. Use the radio to signal the bomber squadron to arrive - but as you do, Böhm will arrive and taunt you. The end result is that Sofia is killed, and Böhm starts his escape.

Stop Böhm from Escaping
After the cutscene, there are two jagers waiting next to the door, one on each side. After they're downed, head through the door. Once the plane starts to launch, quickly run to the left and out to the platform, killing the enemies that are in your way.

Böhm's escape plane should now be on the runway, preparing to take off. To destroy it, aim for the engines - if uncertain, use the binoculars and tag the plane so that you see where to aim. Each engine should go down in two shots.

If the plane does take off, it will make a U-turn to give one last attempt to shoot it down, as it will directly approach your location.

Challenges
There are five challenges
 * Cranium Crusher: Get 20 head shots with the FG42
 * Pressure Cooker: Destroy the 3 Hydrogen Peroxide plant valves in under 5 minutes.
 * No manual Reloading
 * Rapido: Spend less than 2 minutes at a resting Heart Rate
 * The Sound and the Fury: Get 25 or more sound-masked kills.