Basically this chapter was about Kakashi’s growing anger concerning the use of these dead ninja. He felt something for Haku and Zabuza, and now that he is fighting them again he realized that he owes them his thanks for helping Naruto grow. Naturally, the way ninjas thank people is by killing them. Even after Kakashi was slashed across his chest, he still was able to stick his lightning hand through Zabuza, and seal him and Haku for good.
We also see that the battle is not going as good in other places on the front. One mysterious ninja was even able to get all the way to the Supreme Commander, Gaara.