In 1967, just prior to the Six Day War, the Chabad Rebbe introduced the campaign to don tefillin with all Jews. The Rebbe explained that the laying of tefillin instills fear in the enemy, quoting: “Then all the peoples of the earth will see that the name of the Lord is called upon you, and they will fear you.” (Deuteronomy 28:10). The reason why the Tefillin campaign continued is something not many people know: A Jewish man that doesn't don Tefillin in his life has no Share of the World To Come (Rosh Hashanah 17a).