Who is Major Crampas from Effi Briest and what is their importance?

Major Crampas is sent to Kessin as a replacement for the district commandant. Crampas was Innstetten's acquaintance in Paris during the war of 1870. He is described as half-Polish, a gambler and a ladies' man. His wife, Frau Crampas, is a commoner, who is melancholic and jealous of her playboy husband.

Away from his wife, Crampas can be animated and suave. He tells Effi about the war and her husband's stiffness, which prevents him from being one of the boys. He also manipulates Effi into believing that her husband is a pedagogue at heart. Hr then convinces the Innstettens to ride horses together during the fall and continues to ride with just Effi (chaperoned) during the busy election season. They all attend a holiday celebration on Boxer's Day at the Rings, and on the ride home Effi and Crampas are thrown together in a sled. Crampas kisses Effi passionately, beginning a tryst that lasts almost until Innstetten's transfer to Berlin. Innstetten appears to have suspicions but looks the other way. He does, however, caution his wife that Crampas is no gentleman.

Effi keeps Crampas' love letters, but in time, they fall into Innstetten's hands. As a result, Innstetten feels obliged to challenge Crampas to a duel, which the Major accepts, and which in turn, leads to his death. Innstetten divorces Effi and keeps their daughter, leaving Effi embittered over the need to kill someone she does not love and has left behind.