Fight with a happy heart and strong spirit.

The most important six inches on the battlefield is between your ears.

I can't imagine that I would be asked that by the president-elect [Donald Trump], or then-president [Barack Obama]. But it's - I'm very clear. I voted for the change that put the Army Field Manual in place as a member of Congress. I understand that law very, very quickly and am also deeply aware that any changes to that will come through Congress and the president.

Demonstrate to the world there is "No Better Friend, No Worse Enemy" than a U.S. Marine.

I think the core problem is much closer to recognizing where force is of value, where it is useful, and to distinguish that from situations in which war is not useful or is indeed counterproductive.

Once ISIS is defeated, there is a larger effort under way to make certain that we don't just sprout a new enemy. We know ISIS is going to go down. We have had success on the battlefield. We have freed millions of people from being under their control.

Since 9/11 we've been engaged in wars around the world, and General [James] Mattis has been a leading battlefield commander in many of those theaters, including in the April 2004 siege of Fallujah, where the US Marines killed so many people that the municipal soccer stadium in the city had to be turned into a graveyard for the dead.