The Infiltration challenges are not too difficult, I would recommend going for the other miscellaneous achievements before tackling this, that way you'll know your way around the map, making it easier for you to find locations easiest for the challenges.
Challenges can be viewed and tracked in game by pressing ChallengesShhhh!- Ghost kill 5 or more enemies in the Library.
Very easy! If you are wondering, Ghost kill is in other words a silent kill while being undetected. All you have to do is silently take down 5 guys, either by stealth takedown, shooting them with rifle/pistol suppression rounds or welrod.
This must be done in the Library only! The location of the library can be found on the primary objective on the map marked 'Find Box'
I got my kills using the Rifle suppression ammo, note that the enemy dots on the map can be yellow and still count as long as your not detected. Boom! Headshot!- Headshot all Valkyrie Squad members in under 12 minutes.
Hardest challenge of the bunch, the 12 minute timer starts right from the beginning of the mission so you'll want to hurry, saying that you can still stealth some parts and still have enough time on the clock to get those headshots. Their is a total of 14 Valkyrie squad members you must Headshot, they are guys in black heavy armour (similar to the support Jegar) 12 of those you can only kill by completing the side objective 'Summon Squad'-Lure the Fallschirmjager squad using the radio'
First you must get the radio codes from the safe, then summon the squad on the radio. They will come in, 4 guys on foot and the rest in the two light transport tanks. They should all be marked on their way in so should be easy to know which ones to shoot.
The other 2 Valkyrie members are protecting the Propaganda minister, they can be found right next to the summon squad objective marked 'Kill Habermann'
I would recommend getting the two guys protecting the minister first, then summon the squad to get the rest. Here is a clip to show you where you can find the 2 guarding Habermann. I know I kill them with a stealth takedown but that obviously doesn't count as a headshot, was just showing where they are. Then the last part of the clip shows me completing the challenge.
Sorry, this Game Clip has been removed
Don't Stop Breathing- Don't use Empty Lung.
Simple, but if your like me it's always a force of habit using empty lung
All you will need to do is complete the entire mission without using
while aiming down the sights, if you hold your breath by mistake then the challenge will instantly be failed. What I would do is make manual saves as I went along in the mission so if I did accidentally fail, I could reload my manual save with the challenge obtainable again.
If you get through the whole mission without empty lung then you shall have the challenge complete apon completing the mission.A Touch of Glass- Get kills with 3 or more dropped chandeliers.
Again an easy challenge, you can find chandeliers in the Library section of the level at the primary objective on the map 'Find Box'
In the Library itself their are 4 chandeliers hanging from the wall. I would recommend making a manual save just before entering the library in case you make a mistake.
Best thing to do is throw a rock right under a chandelier, luring a helpless troop into your trap. Once he is below it, shoot the chandelier , causing it to drop and kill them, note that this must be done with 3 different chandelier lights, getting a double kill with one light will only count as one.
One chandelier light can be found before the library in the auditorium while going for the Debriefed achievement.
You can check out the location for this by going to TheWelshTurtles guide for the debriefed achievement.
The Debriefed achievement in Sniper Elite 4 worth 122 pointsInfiltration - Multi-Kill the Officers during the tactical briefing in the auditorium
Make sure to give the guide a thumbs up while your there! Man in the High Tower- Kill 20 or more enemies from towers with a flag.
Another simple one, you must kill 20 guys from a tower with a flag above it, these towers are scattered all over the town and usually have a Italian flag hanging from the top, Snipers use these as nests on the mission. You can find a couple in the Primary objective area called 'Free Veriana'
Once in the tower you'll notice you should have a good view of most of that area of the map, I killed 20 all in one go, note that kills made from inside the tower count too.
Here is a location of one of the towers and the one I would recommend using:
Sorry, this Game Clip has been removed
Note that all and individual challenges don't have to be done in one go, for example you can get 10 kills in the tower, complete the mission, then start the mission again and get another 10.