Heavenly host
Heavenly host (Hebrew: צבאות sabaoth, "armies") may refer to the army of Canaanite gods in the original, polytheistic religion of Canaan, Israel, and Judea or an army (Luke 2:13) of angels in the monotheistic Jewish religion that developed in the post-exilic period. It is mentioned both in the Hebrew and Christian Bibles, as well as other Jewish and Christian texts.
Several descriptions of angels in the Bible describe them in military terms, such as encampment (Genesis 32:1-2), command structure (Psalms 91:11-12; Matt.13:41; Rev.7:2), and combat (Jdg.5:20; Job 19:12; Rev.12:7). The heavenly host participate in the War in Heaven and, according to some interpretations, will battle Satan and Satan's own army at the End of Days and be victorious.
Biblical accounts
Book of Joshua
In the Book of Joshua 5:13-15, Joshua encounters a "captain of the host of the Lord" in the early days of his campaigns in the Promised Land. This unnamed heavenly messenger is sent by God to encourage Joshua in the upcoming claiming of the Promised Land: