[A]s Dorothea drove her car-loads of refugees day after day in perfect safety, she sickened with impatience and disgust. Safety was hard and bitter to her. Her hidden self was unsatisfied; it had a monstrous longing. It wanted to go where the guns sounded and the shells burst, and the villages flamed and smoked; to go along the straight, flat roads between the poplars where the refugees had gone, so that her nerves and flesh should know and feel their suffering and their danger. She was not feeling anything now except the shame of her immunity. 
It is with the game of war as it was with the game of football I used to play with my big brothers in the garden. The women may play it if they're fit enough, up to a certain point, very much as I played football in the garden. The big brothers let their little sister kick off; they let her run away with the ball; they stood back and let her make goal after goal; but when it came to the scrimmage they took hold of her and gently but firmly moved her to one side. If she persisted she became an infernal nuisance. [105-6]
From this perspective--and this is clearly reflected in Dorothy's "shame" over her "immunity" (see n. 17)--what is wrong with war, and with women's position in relation to it, is that it is confined to men. War seems to represent, in these passages, a male-only club that women like Sinclair and Dorothy desperately wish to join.
"An Appeal against Female Suffrage." Nineteenth Century 148 ( 1889): 781-88. Reprinted in Free and Ennobled: Source Readings in the Development of Victorian Feminism, edited by Carol Bauer and Lawrence Ritt , 260-62. Oxford: Pergamon Press, 1979.
Cook, Blanche Weisen, ed. Crystal Eastman on Women and Revolution. Oxford: Oxford University Press, 1978.
Gilbert, Sandra M. "Soldier's Heart: Literary Men, Literary Women, and the Great War." Signs 8, no. 3 (Spring 1983): 422-50.
Hartsock, Nancy C. M. Money, Sex, and Power: Toward a Feminist Historical Materialism