What is the meaning of "Forty and Eight"?

La Societe Des 40 Hommes et 8 Chevaux is a French title meaning “The Society of the 40 Men and 8 Horses”. The phrase is derived from the rail cars used during World War I to transport troops to the Western front in France. Each car was supposed to have capacity of, predictably, 40 men and eight horses.
The 40&8, as it is more commonly known, was an organization for Legionnaires who had distinguished themselves through service. The 40&8 is no longer affiliated with The American Legion, although the organization does still exist.

The 40&8 national organization can be contacted at:
Forty & Eight National Headquarters
777 N. Meridian St.
Indianapolis, IN 46206
Tel: (317) 634-1804