His fingers wake, and flutter up the bed.
His eyes come open with a pull of will,
Helped by the yellow may-flowers by his head.
A blind-cord drawls across the window-sill . . .
How smooth the floor of the ward is! what a rug!
And who's that talking, somewhere out of sight?
Why are they laughing?  What's inside that jug?
"Nurse!  Doctor!"  "Yes; all right, all right."
But sudden dusk bewilders all the air—
There seems no time to want a drink of water.
Nurse looks so far away.  And everywhere
Music and roses burst through crimson slaughter.
The ‘sudden dusk’ suggests that the soldier has lost sense of time. The ‘dusk’ is ominous; for the first time we have a hint of the darkness and cold that indicate that this soldier might die. 
 The air is personified here. The dusk ‘bewilders’ it, although it is, of course, the soldier who is bewildered. The dash creates a caesura which might suggest that the young man has drifted back into unconsciousness.