Asking legitimate questions during the Reno Court of Inquiry (the only inquiry on the Little Bighorn ever) was forbidden by the army
source: Athur Unger, The ABCs of Custer's Last Stand, Upton And Sons, 2004, page 218
When Recorder Jesse Lee started to really dig into the questions (to witnesses of the 7th cavalry), Colonel Wesley Merritt (responsible of the Court) called a recess and hauled Lee into a room. Merritt basically told Lee to stop digging or his military career would be over.
Lee followed the orders of Merritt and did not dig anymore, thus preserving the cover-up. It would not be until years later that Merritt would confess that "we had whitewashed it over."