From The Collaborative International Dictionary of English v.0.48:
March \March\, v. i. [imp. & p. p. Marched; p. pr. & vb. n.
Marching.] [F. marcher, in OF. also, to tread, prob. fr. L.
marcus hammer. Cf. Mortar.]
1. To move with regular steps, as a soldier; to walk in a
grave, deliberate, or stately manner; to advance steadily.
--Shak.
[1913 Webster]
2. To proceed by walking in a body or in military order; as,
the German army marched into France.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Marching \March"ing\,
a. & n., fr. March, v.
[1913 Webster]
Marching money (Mil.), the additional pay of officer or
soldier when his regiment is marching.
In marching order (Mil.), equipped for a march.
Marching regiment. (Mil.)
(a) A regiment in active service.
(b) In England, a regiment liable to be ordered into other
quarters, at home or abroad; a regiment of the line.
[1913 Webster]