"no longer required to engage in deeds whose gravity exceeds the demands of their tender years."
direct quote from his speech, hope it helps
Throughout the horrors of his captivity, Wiesel states that he needed to be strong for his father. He needed to survive for his father. After his father's death, he no longer feels as though he has anything to live for. It can be assumed that he no longer paid attention to the world around him. His lack of detail about that is due to the fact that he no longer cared about what was going on.
The Long March started on the 1934-1935, started when Communist forces, surrounded by the Nationalist army. They had to flee their their base in Jiangxi province. Their journey lasted for a year and they arrived to Northern Shaanxi. During that times, they fought hard battles, and when they arrived, out of 80.000 only 8.000 survived.
The direction from Jiangxi, they went North to get to Shaanxi.