Game Info
Vanilla and Gods & Kings
Unique front-line unit of the German civilization. Replaces the Pikeman.
- Common abilities:
- Bonus vs Mounted (100)
Brave New World
Available for purchase in cities after adopting the Mercenary Army Social Policy, or from allied militaristic City-States who offer it as their bonus troop once you have the ability to build Pikemen.
- Common abilities:
- Bonus vs Mounted (50)
- Special abilities:
- No Movement Cost to Pillage
- City Plunder promotion (Steals
Gold Gold equal to 100% of the damage inflicted on a city)
Strategy
In vanilla Civilization V and Gods & Kings, the Landsknecht is mainly interesting for its 
Production Production price, which is one-half that of a Pikeman. This, and the fact that they don't require resources, allows a German player to bring out a number of them very fast. Then it is the old "Zerg rush" strategy, and the Germans can start on their way to a domination victory!
In Brave New World, the Landsknecht becomes available only after adopting Mercenary Army in the Commerce Social Policy tree, but it is now available to all civilizations once they research Civil Service. This unit still retains its half price compared to a normal Pikeman, but in addition, it possesses unique promotions that allow it to pillage improvements at no movement cost and to pillage twice as much 
Gold Gold from cities. These features make the unit an interesting representation of actual real-life mercenaries, only interested in war as far as it enriches them.
More importantly, however, is that the Landsknecht is one of the only units in game (if not the only unit) that can move and attack on the same turn it is purchased!
This unit is great if you need a unit immediately, especially for defense.
Civilopedia entry
The landsknecht were German mercenary pikemen of the 16th century. Created in imitation of the legendary Swiss mercenary pikemen, the landsknecht would eventually supplant them as the best mercenary infantry available in Europe, fighting in almost every major engagement in the 16th century – often on both sides. In battle landsknechts generally carried pikes of up to twenty feet in length. Some few also carried huge two-handed swords or halberds; these were used to chop the heads off of the pikes of their opponents.
Trivia
Landsknecht is often translated as "Servant of the Country." The term was believed to have been coined by Peter von Hagenbach.