The plugboard ("Steckerbrett" in German) permitted variable wiring that could be reconfigured by the operator (visible on the front panel of Figure 1; some of the patch cords can be seen in the lid). It was introduced on German Army versions in 1930, and was soon adopted by the "Reichsmarine" (German Navy). The plugboard contributed more cryptographic strength than an extra rotor. Enigma without a plugboard (known as "unsteckered Enigma") could be solved relatively straightforwardly using hand methods; these techniques were generally defeated by the plugboard, driving Allied cryptanalysts to develop special machines to solve it.