Who is Comrade Harry?

I tried to identify “Comrade Harry” through people Alphaeus named in the letters, but I found no strong connections. “Comrade Harry” was definitely someone that Alphaeus considered not only a brother in the struggle, but also a friend and confidant. There was a moment in the letters, after the loss of close comrades killed in the war, that Alphaeus contemplated his own fate. He relied on, “Comrade Harry” to prepare his family in the event he didn’t return home.