Sanchez

Lieutenant-General Sanchez was a US Army general and a high-ranking UNIT officer.

Biography
Sanchez was in command of at least a UNIT base and possibly UNIT's American branch when the Daleks invaded the Earth in 2009. He had appointed Martha Jones the Medical Director of Project Indigo, an experimental teleportation system which used Sontaran technology. Sanchez and the United Nations declared an Ultimate Code Red when the Dalek message of Exterminate! was conveyed to the human race.

When the Daleks invaded UNIT's base in New York City, Sanchez and another soldier attempted to fight the Daleks as Sanchez ordered Martha to escape by means of the Project Indigo prototype. She took the Osterhagen Key with her. Sanchez was exterminated by Daleks after Martha teleported to safety. (DW: The Stolen Earth)

Within UNIT hierarchy
Sanchez ranked above Colonel Mace and possessed the power to authorise use of the Osterhagen Key. He still took orders from Geneva.

Behind the scenes

 * Sanchez carried a revolver with a ivory style grip much like General George Patton in World War II. Such weapons are considered obsolete in most modern military forces, including the United States Armed Forces and NATO, and it is against regulations to use one as a personal side arm. It is highly unlikely that an elite organisation like UNIT would have standards below that of NATO, or that a U. S. Army general would carry an inferior weapon while on active duty, especially given the nature of the threats UNIT faces.
 * His shoulder patches indicates that he is from the 82nd Airborne Division, as well as a U.S. Army Ranger. However, his uniform does not include a Parachutist's Badge, (which would indicate that he has completed Jump School training), which is a requirement for members of both units. (However, a Master Parachutist Badge can clearly be seen on the left breast pocket of his uniform coat, underneath his ribbons, along with a Pathfinder Badge, in the scene where he approaches Martha saying that Project Indigo is being activated and in scenes thereafter)
 * Sanchez uses the term "quick march" when speaking to Martha. Either he is using the British command in deference to Martha's nationality (the equivalent American term is "double time") or this is another example of British word usage seeping into the dialogue of American characters, such as those in Peri Brown's dialogue.