Conversation so far:
when did Columbus Delano resign?
1875
what did Columbus Delano resign from in 1875?
Secretary of the Interior
why did Columbus Delano resign from Secretary of the Interior in 1875?
Columbus Delano's reputation for personal honesty came under increasing scrutiny as revelations of corruption in the Grant administration continued to be the subject of investigations and media revelations.
was Columbus Delano replaced after he resigned as Secretary of the Interior?
Grant replaced Columbus Delano with Zachariah Chandler, who quickly initiated civil service and other reforms in the Department of the Interior.

Question: what was the corruption?
Self-contained rewrite: what was the corruption Columbus Delano was accused of?