18 And when they came down to him, Elisha prayed unto the LORD, and said, Smite this people, I pray thee, with blindness. And he smote them with blindness according to the word of Elisha.
[AD 373] Ephrem the Syrian on 2 Kings 6:16-23
Elisha prayed before the Lord and said, “strike this people with blindness.” And he struck them with blindness according to the words of Elisha. Ben-hadad, king of the Arameans, sent a large army to surround the city of Dothan and ordered them to arrest Elisha, who lived there at that time. Now his servant saw the army of the Arameans and was horrified. But Elisha opened the eyes of the young man and showed him the ranks of fire that the Lord had erected around him against the Arameans, and his fear disappeared. At the same time [the enemies] were struck in their eyes and did not know the route of their march. They asked Elisha to be their guide; he led them to Samaria, and they were imprisoned inside walls. Then their eyes opened and they realized the danger into which they had voluntarily thrown themselves. But Elisha ordered that nobody should hurt them, and by his command, king Jehoram warmly received them. After offering them a banquet, he sent them back to their land in peace.This is the symbolic meaning [of this passage]: God had predicted through the prophet Isaiah, “The heart of these people was hardened; they have stopped their ears and have shut their eyes, so that they cannot see with their eyes.” The people of Abraham had been blinded by a just sentence of God, because of their perverse will. They asked that the Savior of the world be killed and tried to delete any memory of him completely, but Christ has converted them from their perversity to good behavior. He has delivered his persecutors from their blindness and has given them the bread of heaven. Then he has scattered them through the earth to announce his wonders. Such were those who came back from the mount of Golgotha, beating their own chest. They said to Simon and the other apostles with contrite hearts, “Brothers, what should we do?” And such was Saul, the persecutor of the church whose eyes were open without seeing and whose eyes God wondrously closed but opened again very soon, and to whom he ordered to bring his name before the nations, the kings and the children of Israel.

[AD 397] Ambrose of Milan on 2 Kings 6:16-23
But, as many delight in warfare, which is the most glorious, to bring a battle to an end by the strength of a great army or by merits before God alone? Elisha rested in one place while the king of Syria waged a great war against the people of our ancestors, and was adding to its terrors by various treacherous plans and was endeavoring to catch them in an ambush. But the prophet found out all their preparations, and being by the grace of God present everywhere in mental vigor, he told the thoughts of their enemies to his countrymen and warned them of what places to beware. And when this was known to the king of Syria, he sent an army and shut in the prophet. Elisha prayed and caused all of them to be struck with blindness and made those who had come to besiege him enter Samaria as captives.

[AD 397] Ambrose of Milan on 2 Kings 6:16-23
If, then, justice is binding, even in war, how much more ought we to observe it in time of peace. Such favor the prophet showed to those who came to seize him. We read that the king of Syria had sent his army to lie in wait for him, for he had learned that it was Elisha who had made known to all his plans and consultations. And Gehazi, the prophet’s servant, seeing the army, began to fear that his life was in danger. But the prophet said to him, “Do not fear, for they who are with us are more than they who are with them.” And when the prophet asked that the eyes of his servant might be opened, they were opened. Then Gehazi saw the whole mountain full of horse and chariots round about Elisha. As they came down to him the prophet says, “Strike, O God, the army of Syria with blindness.” And this prayer being granted, he says to the Syrians, “Follow me, and I will bring you to the man whom you seek.” Then they saw Elisha, whom they were endeavoring to lay hold of, and seeing him they could not hold him fast. It is clear from this that faith and justice should be observed even in war; and that it could not but be a disgraceful thing if faith were violated.

[AD 397] Ambrose of Milan on 2 Kings 6:16-23
Elsewhere, also, that is, in the books of Kings we read that Elisha was in Samaria, and suddenly an army of Syrians surrounded and set on him. Gehazi saw them and said to his master, “O master, what shall we do?” And Elisha the prophet said, “Do not fear, for there are more with us than with them.” And he prayed that the Lord would open the eyes of Gehazi. And his eyes were opened, and he saw the mountain full of horses and chariots around Elisha. And Elisha prayed that God would strike them with blindness. And they were struck, and they entered into the city whither they were going, seeing not at all. Surely, you soldiers who have been surrounded have heard that where there is perfidy, there is blindness. Rightly, therefore, was the army of the unbeliever blind. But where there is faith, there is an army of angels. Good, then, is faith, which often exercises its power among the dead. Hence our adversary [the devil] and his legions are daily hurled back by the virtue of the martyrs.

[AD 465] Maximus of Turin on 2 Kings 6:16-23
When the king of Syria wanted to capture the holy prophet Elisha and make him subject to his own authority and surrounded him with many divisions of armed men, Elisha was not terrified or distraught, but said to the servant who served as messenger: “Do not be afraid for there are more with us than there are with them.” O the faith of the holy prophet! He does not fear the enemies whom he sees, since he knows that there are angels with him whom he trusts. He does not dread earthly ambushes, because he knows that heavenly auxiliary troops are there for him. “There are more with us,” he says, “than there are with them.” This is an amazing thing. Holiness merits more defenders from heaven than the foes that immorality leads onto the field. “There are more with us than there are with them.” Behold the merit of blessedness! The prophet makes his announcement about the multitude while the servant is still uncertain of his own salvation. How much more do spiritual eyes perceive than those of the flesh! One sees the number of the armed men, while the other perceives the sign of their protection. How great is the divine mercy! A blessing is delivered to people, but it is not seen. They receive help while they are in danger, but they do not know it. For this is the mercy of the Savior, that he intervenes for salvation and in doing so he does not allow himself to be seen. He is sensed by the benefits that he bestows, but not with the eyes.So they are in error who think that when a battle is waged successfully, they have overcome through their own strength. For they should know that adversaries are conquered by merits rather than by strength, and they are overcome not so much by power as by holiness, as holy Elisha was overcoming his enemies by prayer and not by arms. For when he was telling his servant to banish his fear, that those defending them were more than those opposing them, not even then was the servant’s fear able to be dispelled. Then Elisha prayed to the Lord, saying: “Lord, open his eyes so that he can see!” And his eyes were opened and he saw, and there was a whole mountain filled with horsemen.” So the prophet’s prayer opened the servant’s eyes. It is no surprise that a prayer opened his eyes to see an army, since prayer opened heaven so that an army came. It is no surprise, I say, if the God who was promising new auxiliaries implanted new eyes. Or why could he not bring forth an army of seers who furnished an army of angels for battle? Why, I say, could not he, who through his merits penetrated the darkness of the clouds, have wiped away the dullness from the servant’s eyes? Certainly then holy Elisha granted safety by this act to the fearful servant to whom he had restored the brightness of sight.

[AD 1781] Richard Challoner on 2 Kings 6:18
Blindness: The blindness here spoken of was of a particular kind, which hindered them from seeing the objects that were really before them; and represented other different objects to their imagination: so that they no longer perceived the city of Dothan, nor were able to know the person of Eliseus; but were easily led by him, whom they took to be another man, to Samaria. So that he truly told them, this is not the way, neither is this the city, etc., because he spoke with relation to the way and to the city, which was represented to them.