Seeing Double (Check)
There are few tactics more powerful than double check. Not only can it end a game abruptly, it's often hard to see it coming until some sacrifice reveals it lurking in the background. In the game below John Schulten, a German-American master of the early-middle 19th century finds himself on the wrong side of a surprise sacrifice instigated by Bernard Horwitz, a noted chess problemist and member of the famous Berliner Pleiades.
Black to move: