In "The Bronze Bow," what does Daniel expect to lose in order to gain Joel's freedom?
Daniel expects to lose his relationship with Rosh, his place among Rosh's band, and any further contact with Samson. Although he knows the mission is a high-risk proposition, he does not expect any of the twenty young men—including himself—to lose their lives in their attempt to save Joel. He expects to be able to confuse the Romans and free Joel. These expectations are only partially met.
Daniel abandons Rosh and will never consider him his leader again. He declares, "I am not one of your men. Not any longer." As he leaves, he knows he is finished with his association with the band on the mountain. When Joktan volunteers to leave with him, he accepts him, but he regrets that Samson has not appeared so he can at least say goodbye to him. He believes he will never see him again.
When discussing his plan with the nineteen others in his group, he explains how they will surprise and confuse the Romans long enough for him to rush down, break Joel's chains, and return with him. Although he knows all the boys are willing to give their lives for Joel's rescue, he determines as their leader that none of them will die. Only for a moment he allows himself to think of the ultimate battle that will throw off Roman rule. Although he brushes that thought aside, there is no inkling that he expects to die in this skirmish even though he knows it is very dangerous.
What really happens smashes Daniel's expectations. Despite his resolve to keep all the boys safe, Nathan dies. And despite his assumption that he would never see Samson again, Samson appears and sacrifices himself to save Joel and Daniel.
So in the end, Daniel loses a good friend in Nathan, he loses Samson—although he did get to see him once more—and he loses his belief in his ability to fight off the Romans. The losses change Daniel's whole perspective because "the eager confidence of the night before would never be regained."
After Joel is taken by the Romans, Daniel determines to rescue him. He discovers that he cannot count on Rosh, who considers people expendable in the larger scheme of the war, and so he gathers a few people together and stages an ambush. Daniel is not stupid, and knows that the rescue is practically guaranteed to be a suicide mission, but he does not want to be the kind of person who sits back and allows his friends to be killed for nothing.
It was no flimsily-guarded caravan they awaited. And behind him was no tight-knit band that would move with precision and cunning, only a cluster of untried boys... Still, he could count on them. He knew that every boy in the band was prepared to give his life. It was up to him, the one they had chosen leader, to see that none of them had to.
(Speare, The Bronze Bow, Google Books)
Daniel has lost Rosh, the man he considered an almost infallible moral compass, because Rosh was willing to let Joel die to preserve the cause. Daniel has now discovered that he is not like Rosh at all; Daniel believes in himself and his men as individuals and as a team, not as pawns to be sacrificed. In the pursuit of his moral obligation to rescue Joel by any means possible, Daniel is willing to sacrifice himself to avoid becoming a coward like Rosh.