"Guns! Far and near" - juxtaposition illustrates the unpredictability of war.
Naivity on the front: "Upturned faces appear" - disillusioned and unprepared
No punctation "there is a hurrying of feet And whirled athwart gloom White fingers of alarm Point at last there Where illumined and dumb A shape suspended Hovers, a demon of the starry air!" - Rapid conversion from normality to action
"Sinister fancy" - oxymoron indicates both fascination and horror of citizens
Sacriligious - "It charms like a snake"
"Strikes not with fear" - Ardent eyed - More fascinated than terrified
"To a deep elation And a quivering pride" - Attitude switches. Now homefront are excited by the spectre. Attitude to war is unconventional - differs from front line POV.
Final stanza - optimistic perspective on death. Essentially says we are doomed but at least "we are neared to them Thank we God" on the frontline - Wanted to feel a part of the horrors. Shocked --> fascinated ---> doomed ---> accepting.