You get this achievement upon completion of the second story mission. This mission takes a little bit longer to complete than the first, as there is two tricky objective that you need to be cuatios on. They are Destroy the Ammo Cache, and the area leading up to Destroying the Communications Antenna and Radio. In addition to the previous 3 objectives, you will also have to Sabotage some Fuel Containers, these 4 objectives can be completed in any order.
Once you have that first part of the mission completed, you will be directed to Assemble with 5th Army Demo Team where you will be ambushed. You must defeat this ambush in order to progress. Once that is done, you can move on to the final part of the missin. Go and Assemble with Corporal Kish, where you will proceed tascend the hilltop temple, destroy the AA gun that's up there, and blow up two fifty gallon drums to signal where the P-40 Warhawks must drop their payload. After this the mission will end.
I hope this solution helped! Leave a comment letting me know if there is any room for improvement! Thanks.