From August 1900 to May 1902 Eugen Büchel studied philosophy at the Jesuits' Sacred Heart College in Prairie du Chien, Wisconsin.
On December 10, 1909, Father Superior Büchel buried Oglala-Chief Red Cloud in the cemetery of Holy Rosary.
Over thirty years earlier, Red Cloud had demanded "Black Robes" and "Holy Women," i.e. Catholic priests and nuns, for the Oglala from the U.S. authorities.
In collaboration with Ivan Stars and other Lakota catechists, Buechel collected oral histories, now published bilingually, and cultural objects with related information, now preserved at the Buechel Memorial Lakota Museum, St. Francis, South Dakota, and first displayed at the Mission in 1921.
In 1924, Buechel published his first notable work in Lakota, his Bible History, which included a selection of texts modeled after the German Biblische Geschichte.
Meanwhile, he gained recognition as a linguist through his correspondence with anthropologists like Franz Boas and Lakota Ella Cara Deloria.
Buechel's linguistic work today is recognized and used as one of the most important sources for the Lakota language by all who want to learn it or have a general concern in its preservation and development.
Among the Jesuits today, he is increasingly perceived as a role model because of his respectful attitude towards the Lakota as a people and as individuals.