If you are new to martial arts and interested in learning, just find a decent school that you find appealing. This is the standard advice on this site for all beginnersThis is the standard advice on this site for all beginners.
In the United States, the Marine Corps Martial Arts Program (MCMAP) and Modern Army Combatives Program (MACP) programs are built from multiple distinct martial arts sources. MCMAP has(had?) a list of martial arts that are approved for meeting a higher rank requirement for civilian martial arts training:
Categories for civilian (MCMAP approved) martial arts are: grappling or throwing arts; striking arts; and weapons arts. The grappling or throwing arts are, but not limited to: Judo, Jujitsu, Sambo, Hap Ki Do, and Ai Ki Do. Striking arts are, but not limited to: Karate, Tae Kwon Do, Kickboxing, Muay Thai, Kung Fu, and Capoiera. Weapons arts are, but not limited to: Kabudo, Ascrema, Cali, Kendo, and Aiedo.
As you can see, this list has many martial arts, and is expressly not limited. Any decent martial arts school will teach at least one of grappling or throwing, striking, or weapons.
Modern warfare is based around weapons that kill at a distance, like cruise missiles, artillery, and firearms. It is overwhelmingly more important that soldiers learn to shoot and not get shot than fight hand-to-hand. Soldiers will learn hand-to-hand combat techniques in basic training, but hand-to-hand combat is a not a priority. The primary tactic (Option 1) in MACP is to make space so you can shoot with your standard-issue rifle (primary weapon). Civilians do not have standard-issue rifles that are carried at all times, so obviously martial arts training will differ between military and civilians. The US military does not expect you to know any of this before you show up.