The Rebbe's guidance for Jewish soldiers — in the IDF and in other armies — and on questions of army service:
Tefillin protects. Putting on tefillin every day brings special protection for a Jewish soldier and his safe return (IK 1496, 2145, 2862, 9717, 9722). Share this with fellow soldiers and their families (IK 9717, 9959).
Holiness makes the army strong. When a camp is kept holy, it enjoys Divine protection (IK 124). Keeping Torah and mitzvos in military service strengthens both the soldier and his unit (IK 5673, 9950), and a Jewish soldier carries added responsibility to maintain holiness for those around him (IK 5903, 10737). Keep up daily mitzvos, Torah study — by heart where needed — prayer and Tehillim throughout one's service (IK 913, 1187, 6101, 6558). For practical halachic questions in the army, see Machaneh Yisrael (IK 2080).
Inspire your fellow soldiers. Every Jewish soldier can influence his comrades, even those who seem distant (IK 1197, 2792, 9656). The disciplined setting of the army is a special opportunity to connect soldiers to Torah and mitzvos (IK 5113); provide them with kosher food, tefillin, Torah texts and a Sefer Torah (IK 059, 134, 7170, 7780). Military chaplains should combine heartfelt words with practical mitzvos (IK 8941, 5782, 8003).
A lesson in obedience. Military discipline — obeying before fully understanding — is a model for accepting the yoke of Heaven (IK 3611, 7042, 9269, 9998, 10294, 10389).
Who serves. Yeshiva students in Eretz Yisrael should not be drafted; their Torah study protects the Land and its people (IK 7736). Religious girls are exempt, and women may not serve in the army according to Torah law (IK 8756, 10055). Teaching positions for avrechim as an alternative to army service should be considered thoughtfully (IK 5593).
See also: Land of Israel – Security and the wholeness of the Land; Parenting – Raising daughters.