Who is the commander of the Lord's army?
"And it came to pass, when Joshua was by Jericho, that he lifted his eyes and looked, and behold, a Man stood opposite him with His sword drawn in His hand. And Joshua went to Him and said to Him, "Are You for us or for our adversaries?" So He said, "No, but as Commander of the army of the LORD I have now come." And Joshua fell on his face to the earth and worshiped, and said to Him, "What does my Lord say to His servant?" Then the Commander of the LORD'S army said to Joshua, "Take your sandal off your foot, for the place where you stand is holy." And Joshua did so" (Joshua 5:13-15).
The Bible does not state who the person is, though we are presented with one hint: Joshua fell down and worshiped him without rebuke. We know that men are not to be worshiped (Acts 10:25-26) and neither are angels (Revelation 22:8-9). Thus we must conclude that the person was divine, that is, a part of the Godhead (Matthew 4:1).
A few verses later, in Joshua 6:2, the speaker is referred to as the Lord (Yahweh). Now we can argue whether it was the commander or God speaking through the commander and not come to a conclusion since both forms of address are done in other places. However, it does add evidence to the other points made.
Also, we note that by the commander's presence, the ground was made holy -- something usually only associated with God.
In John's vision in Revelation, Jesus is portrayed as leading a great army, starting in Revelation 19:11. Thus, most assume that the Commander was Jesus.