The article almost seems to imply that Truman ordered the military to be integrated because of the Indian wars. Shoddy writing.
IIRC, it was specifically after the Battle of the Bulge in the winter of '44, and at the urging of General Patton. Allied manpower was running dangerously low, and Patton offered his black support troops the opportunity to fight. Many of them even gave up rank to do so.
One crew in particular (cf Stephen Ambrose, "Citizen Soldiers"), were infantry. They killed a German soldier who had a panzerfaust (sp?). They then ran onto the battlefield, used the panzerfaust to destroy a Tiger tank, and were themselves killed by German fire.
True heroes, they were.
Another interesting point is that some time ago the military used to guard the Mexican American border...