The US 7th Cavalry Regiment was a cavalry 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. It was defeated at Little Bighorn.
As the USS Enterprise-D approached the planet Nelvana III in 2366, which was under suspicion of being the site of a Romulan military build up, William T. 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 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")