But, the most controversial and difficult stand Dr. King took the final year of his life was against the war in Vietnam. Other civil rights leaders urged him to remain silent on the issue, not to alienate President Lyndon Johnson, who had been their best friend on civil rights.

Martin Luther King hated violence. He believed that violence "is a descending spiral, begetting the very thing it seeks to destroy," and that "returning violence for violence multiples violence, adding deeper darkness to a night already devoid of stars . . . He also believed "an eye for eye leaves everybody blind."

So, beginning in April 1967, one year before he died, Dr. King, the Nobel Peace Prize winner, turned this message into an impassioned plea against the war in Vietnam. Indeed, from that point on he questioned the whole rationale for war in general. From the gospel song "Down by the Riverside," Dr. King repeated the line: "I Ain't Gonna Study War No More."

Today, at the Defense Department, how do we honor and respect Dr. King's message and legacy and reconcile it with our mission? We are a nation at war, and it is the responsibility of this Department to prosecute that war.

People like to speculate about what Dr. King would believe and say if he were alive today.

I believe that if Dr. King were alive today, he would recognize that we live in a complicated world, and that our Nation's military should not and cannot lay down its arms and leave the American people vulnerable to terrorist attack.

To our individual servicemen and women who wonder whether their mission is consistent with Martin Luther King's own message and beliefs, I refer you again to his very last speech in Memphis, the night before he died.

In it Dr. King talked about Jesus' parable of the Good Samaritan on the dangerous road to Jericho. With great effect Dr. King drew a parallel between the priest and the Levite who passed by the man on the road to Jericho, beaten and robbed and in need of aid, and failed to help him, and those in Memphis in April 1968 who hesitated to help the striking sanitation workers because they feared for their own jobs, for their own comfortable positions in the Memphis community.

He criticized those who are "compassionate by proxy," and said to those in the audience in Memphis that night "The question is not, if I stop to help this man in need, what will happen to me? The question is, if I do not stop the sanitation workers, what will happen to them."

In 2011, I draw the parallel to our own servicemen and women, deployed in Iraq and Afghanistan and elsewhere, away from the comfort of conventional jobs, their families and their homes. Those in today's volunteer Army, Navy, Air Force, and Marine Corps have made the conscious decision to travel a dangerous road, and personally stop and administer aid to those who want peace, freedom and a better place in Iraq, in Afghanistan, and in defense of the American people. Every day our servicemen and women practice that "dangerous unselfishness" Dr. King preached on April 3, 1968.

In accepting his own Nobel Peace Prize in 2009, our President recognized that, in response to an unprovoked terrorist attack, war is inevitable to secure peace, and that the role of the military is to keep peace.

The irony of next Monday is that Mrs. King's dream of a national holiday for her husband has become a reality; Dr. King's dream of a world at peace with itself has not.