The US 7th Cavalry Regiment was an active unit of the United States Army that was deployed in the Ancient West, during Earth's late 19th century, under the command of George Armstrong Custer.
As the USS Enterprise-D approached the planet Nelvana III, which was under suspicion of being a site of a Romulan military build up, William Riker commented on the lack of resistance, during their approach, stating that he "would've expected a greeting party." Riker's comment reminded Jean-Luc Picard of the Custer, when his 7th Cavalry arrived at the Little Bighorn; a historical situation that very much resembled the situation the crew of the Enterprise looked to face. (TNG: "The Defector")