After WW II and the Korean War, the Italian Mafia especially, attempted to recruit from this pool by making veterans and war heroes offers they could not refuse. Outlaw gangs formed by WW II veterans included the first Los Angeles African American gang the "Purple Hearts" founded by the famous boxer and Army veteran Geronimo Jordan, and the infamous gang of bad boys the "Pissed Off Bastards of Bloomington" (or Berdo) (POBOBs) in San Bernardino, which became the Hells Angels Outlaw Motor Cycle Gang.
Firsthand Experience
When I arrived in Vietnam in February 1967 as an MP with Company A of the 504th, I was lucky enough to be attached to the 101st Airborne Division in the Central Highlands. There was an MP contingent assigned to every infantry unit. There I found that several of the best fighting units had a significant representation of former gang members from New York, Chicago, and Los Angeles. I was especially impressed with a platoon made up of mostly African American soldiers from Chicago who called themselves the "Head Hunters." The Viet Cong greatly feared these troopers and even placed a special bounty on their lives. Later, I was attached to the 4th Division, the 1st Cavalry, and MACV. I found the same kind of ex-gang members in combat fire teams in each of these units.
I believe that many young men today instinctively reject the modern pacifist, self-centered, and materialistic American culture. They often seek membership in gangs as a "positive" setting which allows them to express some of the traits that make them good gang members: self defense skills, team unity, courage, loyalty, and self sacrifice. Once they give up the twisted loyalty to their former street gang, they often make good soldiers utilizing these same traits. I have a brother-in-law who was a Marine Corps Drill Instructor during the Southeast Asian conflicts. He often joked that "Uncle Sam loved his Hispanic Children", and that USMC, in this case, stood for "Uncle Sam's Mexican Children."
But when I became a Deputy Sheriff and was assigned to patrol in East Los Angeles in 1974, I found one of these Vietnam combat veterans had armed the Little Valley street gang with Browning High Power high capacity 9mm handguns, while we were still armed with S&W .38 revolvers. He was teaching them ambush tactics and escape and evasion techniques. Later, when I was assigned in Compton's Lynwood Station in 1978, we had a U.S. Army Reserve unit next door to the Sheriff's station. This unit was made up of mostly Blood and Crip gang members. This was not a good thing.