Critical listening is a form of listening that envolves analysis, synthesizing, and judgement. It is specially useful in situation that have many different opinions and points of view being shown in a single conversation and you need to take something from it objectively, but it is always a good way of listening to information generally speaking.
Summary. The poem tells the story of a brigade consisting of 600 soldiers who rode on horseback into the “valley of death” for half a league (about one and a half miles).