Army Chief of Staff (number of stars depend on rank)
flag-it-army-chief
(Courtesy of Flags Of The World)

Marshal
flag-it-army-marshal(Courtesy of Flags Of The World)

General of an Army
flag-it-army-general-army(Courtesy of Flags Of The World)

General of an Army Corps
flag-it-army-general-corps(Courtesy of Flags Of The World)

General of an Army Division
flag-it-army-general-div(Courtesy of Flags Of The World)

General of an Army Brigade
flag-it-army-general-brigade(Courtesy of Flags Of The World)