John Gill Commentary 1 Chronicles 5:18

"The sons of Reuben, and the Gadites, and the half-tribe of Manasseh, of valiant men, men able to bear buckler and sword, and to shoot with bow, and skilful in war, were forty and four thousand seven hundred and threescore, that were able to go forth to war." — 1 Chronicles 5:18 (ASV)

The sons of Reuben, and the Gadites, and half the tribe of
Manasseh
These all joined together, living together on the one side of Jordan:

of valiant men, men able to bear buckler and sword, and to shoot with
bow, and skilful in war ;
strong able bodied men; and not only able to bear and carry arms, sword in one hand, and shield in another; but were men of valour and courage, and had military skill, and knew how to handle their arms to advantage:

[were] four and forty thousand seven hundred and threescore, that went
out to the war :
that used to go out when there was occasion, and did at this time.