The large knife was used for many
purposes in early America, both martial and civilian. Bowie knives
that were used on the frontier were more often employed as tools in
everyday life than weapons. It was joked that a frontier Bowie knife
should be "sharp as a needle, have an edge like a razor, chop wood
like an axe, and be wide enough to paddle a raft with." It should be
the all around tool for survival in the woodlands.
The D-Guard Bowie, however, is a design best suited for martial
application.
The D-Guard style of Bowie was a pure fighting knife most commonly
seen in the South during the American Civil War. This style has not
often been replicated in American knives since. The W.W.I
brass-knuckle trench knife is pale in comparison to either of these
authentic ACW Bowies from the War Museum down in
Virginia.
Perhaps the weapon most like the D-Guard Bowie, and familiar to many martial artists is the Southern Chinese Butterfly Sword (as used in Wing Chun and other arts). These have the same characteristic hand protection and top trapping guard, although the D-Guard Bowie has a slimmer and longer blade profile than most Butterfly Swords. The D-Guard Bowie also has a top cutting edge, which most Butterfly Swords do not.
The D-Guard Bowie serves as much as a psychological aid in combat as a physical one. The great Captain Fairbain said about the Smatchet (a large combat knife suited to the British sensibilities)
"The psychological reaction of any man, when he first takes the weapon in his hand, is full justification for its recommendation for use as a fighting weapon. He will immediately register all the essential qualities of a good soldier - confidence, determination, and aggressiveness."
The D-Guard Bowie is the same way as a fighting knife. With the sorts of close-quarters fighting and deployment that the military does today, wouldn't it make more sense to give ground troops back-up weapons like this? Weapons that are intimidating to the foe, inspire confidence in the soldier and are powerful as hell in a fight!