Glen A. Doherty, a security contractor and former member of the Navy SEALs, was killed in Libya on Sept. 12, 2012, while defending the American Mission in Benghazi, Libya. During a memorial service for Mr. Doherty and the three other Americans killed in the attack — the Ambassador J. Christopher Stevens, Tyrone S. Woods and Sean Smith — President Obama said of Mr. Doherty: “He believed that his life he could make a difference, a calling that he fulfilled as a Navy SEAL…in Benghazi, as he tended to others, he laid down his life, loyal as always, protecting his friends.” Mr. Doherty’s best friend and former SEAL Team 3 comrade, Brandon Webb, has written a goodbye letter that we are publishing in full. —At War