Analysis of Marching (As Seen From the Left File)

My eyes catch ruddy necks
Sturdily pressed back -
All a red brick moving glint.
Like flaming pendulums, hands
Swing across the khaki -
Mustard-coloured khaki -
To the automatic feet.
We husband the ancient glory
In these bared necks and hands.
Not broke is the forge of Mars;
But a subtler brain beats iron
To shoe the hoofs of death,
(Who paws dynamic air now).
Blind fingers loose an iron cloud
To rain immortal darkness
On strong eyes.