What happens when Chamberlain fills a hole in the line where two Maine soldiers have just been killed?

From the text:

After a while brother Tom found him, sitting in the rain, and sat with him and shared the darkness and the rain. Chamberlain remembered using the boy to plug a hole in the line, stopping the hole with his own brother’s body like a warm bloody cork, and Chamberlain looked at himself. It was so natural and clear, the right thing to do: fill the gap with the body of my brother. Therefore Tom would have to go, and Chamberlain told himself: Run the boy away from you, because if he stays with you he’ll die. He stared at the boy in the darkness, felt an incredible love, reached out to touch him, stopped himself.