Gabriel is the herald of the Incarnation of the Son of God. He is one of the seven archangels who stand before the throne of God. He appeared to Zacharias to announce the birth of the Forerunner. Gabriel said of himself: I am Gabriel, that stand in the presence of God (Luke 1:19). His name Gabriel means “man-God.” The Holy Fathers, in speaking of the Annunciation, comment that an archangel with such a name was sent to signify Who He was, and what He would be like, Who would be born of the All-pure one. He would be the God-man, the mighty and powerful God. Some of the Fathers understood that this same Gabriel appeared to Joachim and Anna concerning the birth of the Virgin Mary, and that Gabriel instructed Moses in the wilderness to write the Book of Genesis. The Holy Fathers say that Gabriel belongs to the first and greatest order of heavenly powers, that is, the Seraphim, since the Seraphim stand closest to God. He is, therefore, one of the seven Seraphim closest to God. The names of the seven are Michael, Gabriel, Raphael, Uriel, Salathiel, Jegudiel, and Barachiel. To this number some add Jeremiel. Each one has his own particular service and all are equal in honor. Why did God not send Michael? Because Michael’s service is to suppress the enemies of the Faith of God, while Gabriel’s is the mission of announcing the salvation of mankind.
Source: St. Nikolai Velimirovic, The Prologue of Ohrid – Volume One.
O Commanders of the Heavenly Host, we the unworthy beseech you, that through your entreaties you will fortify us, guarding us in the shelter of the wings of your ethereal glory, even as we fervently bow before you crying: “Deliver us from all danger, as Commanders of the Powers on high!”
Supreme Commander of God and minister of the Divine glory, guide of men and leader of the bodiless hosts: Ask for what is to our profit and for great mercy, since thou art Supreme Commander of the bodiless hosts.