In T.H. White's The Once and Future King, the reader sees Arthur learning about life. At the beginning, he believes that being a knight is the most important thing he can do. With Merlyn, he learns from the perspective of various animals ways to look at the world differently.
On situation where Wart (Arthur) shows leadership is when his foster brother, Kay, forgets his sword for the tournament. Kay considers himself much more sophisticated than Wart, but can't even remember his sword. When his father realizes that his son is ill-prepared, he tells him to go get his weapon, but Kay tells Wart, his "squire," to do it for him. Wart is not happy, but assumes the responsibility.
"Better go and fetch it," said Sir Ector. "You have time."
"My squire will do," said Sir Kay. "What a damned mistake to make! Here, squire, ride hard back to the inn and fetch my sword. You shall have a shilling if you fetch it in time."
The Wart went as pale as Sir Kay was, and looked as if he were going to strike him. Then he said, "It shall be done, master..."
Wart is insulted that his "brother" would call him "squire" and offer him a reward as if Wart were nothing to him. However, he does what he must, assuming the responsibility that Kay did not.
When he returns and finds the inn locked up, he is uncertain as to what he should do, for everyone is at the tournament and the inn is boarded up tight. If assuming another man's responsibility in order to get "the job done" is not enough to indicate his sense of leadership, we see it again when Wart realizes that if he does not find a sword, Kay will be in trouble. Wart pronounces:
...he shall have a sword of some sort if I have to break into the Tower of London.
In truth, Wart could simply have returned to Kay empty-handed, and no fault would have been attached to him, but Wart decides to solve the problem one way or another. Destiny steps in and leads Wart to the churchyard, where there is a stone with an anvil on it, and sticking out of the anvil is a sword.
"Well," said the Wart, "I suppose it is some sort of war memorial, but it will have to do. I'm sure nobody would grudge Kay a war memorial, if they knew his desperate straits."
And so, as legend has it, young Arthur pulls the sword from the stone.
Having done so, he returns the sword to Kay and tells him where he got it. Kay is aware of the implications of removing the sword from its resting place and tries to convince his father that he freed the sword—giving no credit to Wart. For Wart, taking the credit is not important. Completing the task before him is more important to Wart than who gets credit for it, and this is also a sign of leadership.