Regarding this post, Menachem Butler correctly noted that I had forgotten the recent article by Dr. Judith Bleich in Tradition on this very subject (link - subscription required but note that you can now subscribe online). Dr. Bleich quotes a number of authorities who were opposed to enlistment and/or looked negatively on conscription. On the other side, she quotes a few authorities who looked positively on army service: R. David Tzvi Hoffmann (Melamed Le-ho'il, Orach Chaim 42-43), R. Samson Raphael Hirsch (Horeb, sec. 609) and R. Moshe Shmuel Glasner (the "Dor Revi'i" in Tel Talpiot, no. 104). She did not quote the position of Rav Herzog that I translated in the previous post.