….And Moshe said to Yehoshua, “Choose men for us, and go out and fight against Amalek” – Shemot 17:9

וַיֹּאמֶר משֶׁה אֶל יְהוֹשֻׁעַ בְּחַר לָנוּ אֲנָשִׁים וְצֵא הִלָּחֵם בַּעֲמָלֵק  – שמות יז, ט

The Ananei Hakavod, the protective Clouds of Glory, sheltered all Bnei Yisrael who lived and traveled within them from enemy attack. Amalek was capable of attacking only “the stragglers behind you” who were expelled from the Cloud on account of their sins (see Rashi on Devarim 25:18). Therefore, Moshe instructed Yehoshua to form an army and “go out and fight against Amalek,” as saving these outcasts from Amalek’s attackinvolved leaving the protective Cloud, as Rashi explains here.

This explains the Midrash that gives Yehoshua’s lineage to Yosef (Yehoshua was from the tribe of Ephraim) as the reason why Moshe chose him to lead this battle. For Yosef’s spiritual identity was exemplified in this campaign to save wayward Jews and bring them back into the safe confines of the Ananei Hakavod.

The name Yosef expressed his mother Rachel’s prayer for more children: “יֹסֵף ה’ לִי בֵּן אַחֵר—May G-d add [yosef] another son for me” (Beraishis 30:24). Notably, her request was not only that G-d grant her an additional child, but that He grant “בן אחר,” which literally means, “an other child.” Chassidus explains this to mean that Yosef, the bearer of this name, represents the ability to transform even someone who is an “אחר,” an “other,” into a “בן,” a son. Yosef’s specialty is affecting even someone for whom G-d seems foreign and who behaves in a manner that is “other” – foreign – to a Jew, bringing him to recognize that he is truly a “son,” a child of G-d, and drawing him to live his life as such.

Therefore, it was Yehoshua, from the offspring of Yosef, who was chosen to lead the war against Amalek. For the willingness to leave your own sheltered environment in order to save those who are “outside the cloud” and the ability to bring them back into G-d’s miraculous Ananei Hakavod is inspired by and drawn from the spiritual identity of Yosef.

—Likkutei Sichos, vol. 26, pp. 87-88