Whilst he [Alcibiades] was very young, he was a soldier in the expedition against Potidae, where Socrates lodged in the same tent with him, and stood next to him in battle. Once there happened a sharp skirmish, in which they both behaved with signal bravery, but Alcibiades receiving a wound, Socrates threw himself before him to defend him, and beyond any question saved him and his arms from the enemy, and so in all justice might have challenged the prize of valour. But the generals appearing eager to adjudge the honour to Alicibiades, because of his rank, Socrates, who desired to increase his thrist after glory of a noble kind, was the first to give evidence for him, and pressed them to crown him, and to decree to him the complete suit of armour. Afterwards, in the battle of Delium, when the Athenians were routed, and Socrates with a few others was retreating on foot, Alcibiades, who was on horseback, observing it, would not pass on, but stayed to shelter him from the danger, and brought him safe off, though the enemy pressed hard upon them, and cut off many.
tl;dr:
Socrates saves Alcibiades in battle; the Athenian generals overlook Socrates and want to award Alcibiades because he has a higher rank; Socrates supports the decision, hoping that it would make Alcibiades want to accrue more honors, causing him to be more noble and courageous on the battlefield; Alcibiades later risks his own life to save Socrates on the field, implying that Socrates benefited wildly from his earlier decision.
Source:
Plutarch, John Dryden, and Arthur Hugh Clough. "Alcibiades." Plutarch's Lives. New York: Modern Library, 2001. 262-63. Print.
Further Reading:
Ἀλκιβιάδης Κλεινίου Σκαμβωνίδης (Alcibiades, son of Cleinias, from the deme of Scambonidae)
Socrates was quite heavily bend on the "duty as soldier" stuff. He volunteer way past the age when he was mandated to go. Also, he focused on the duty to your polis in his teachings. Every source agrees he was very good soldier.