On the eve of the Six Day War in 1967, when the entire world predicted Israel's demise, the Rebbe initiated the tefillin campaign, and assured us that great miracles are in store. He quoted the Divine promise that in the merit of the mitzvah of tefillin, "all the nations of the world will see that the name of G-d is called upon you, and they will fear you" (Deuteronomy 28:10).
The mitzvoh of tefillin gives special help in not being afraid of the enemy. The tefillin of the hand is placed opposite the heart, which represents oneís emotions. The tefillin of the head is placed on the head, which represents oneís intellect. The spiritual meaning of these two parts of the tefillin is that oneís emotions and oneís intellect must be subjugated to G-d, Who commands the mitzvos in general, and the mitzvah of tefillin in particular. This subjugation to G-d brings G-dís blessings in what one does with his hands and with his mind (which is in the head). It is especially effective in helping soldiers who are fighting in the war to achieve victory in the war.
(The Rebbe, October 26, 1973)
Click here to learn more about tefillin.