Final answer:
The word "march" is likely used by the poet to connect the characters' actions to the structured progression of soldiers, emphasizing military undertones and the theme of struggle.
Step-by-step explanation:
The poet most probably chooses to use the word "march" to extend the image of the approach as a war zone.
This choice of diction connects the movement of characters within the poem to the structured and deliberate progression of soldiers, which intensifies the gravity of the situation they are facing.
The term "march" also aligns with the historic use of The Sacred Spot as a marching song by soldiers, further emphasizing the military connotations and thematic elements of struggle, discipline, and progression within a challenging environment.