Who is Francis MacNamara from Unbroken: A World War II Story of Survival, Resilience, and Redemption and what is their importance?

Francis MacNamara was one of the survivors of the crash of the Green Hornet. While isolated on the raft, MacNamara sometimes lost control of his emotions and cried that the three men were bound to die. In a panic one night, he ate their entire supply of emergency chocolate. MacNamara helped the three survive by fighting off sharks and by pumping and bailing water while they repaired their bullet-ridden raft. He died before the men were rescued and his body was buried at sea.