President-Elect Donald J. Trump showed excellent judgment in appointing Marine general James N. Mattis to lead the Department of Defense for two independent reasons.

First, General Mattis is eminently qualified to lead the government's largest and most expensive bureaucracy.  The general has led the United States Joint Forces Command and the United States Central Command and as such can be said to know the Pentagon like the back of his hand.  General Mattis will hit the ground running on day one.  His status as a four-star means that the Joint Chiefs will quickly accept him as their peer.

Second, the president-elect was absolutely right to first appoint a secretary of defense rather than a secretary of state.  This is the right priority order, because it is our military strength that qualifies our country as the world's top superpower.  Soldiers win battles; diplomats sometimes (Vietnam) lose the war.  State telling Defense what to do, which has been the Obama model, is a case of the tail wagging the dog.

The question now arises: which candidate for the position of secretary of state would be most compatible with General Mattis?  The president-elect will want to make sure that State and Defense are in sync.  The Benghazi fiasco was due in no small measure to Hillary Clinton getting priority over Leon Panetta at Defense.  Previously her husband's White House chief of staff, Panetta probably felt subordinate to the former first lady.

With these criteria in mind, let us see how four candidates fare: Governor Mitt Romney, General David Petraeus, New York mayor Rudy Giuliani, and Ambassador John Bolton.

Romney, Petraeus, and Giuliani would not hit the ground running day one.  By the time they are up to speed, more than likely several months later, State's career diplomats will have figured out how to maneuver around whatever changes might come their way.  This would happen because the local team inherently has a field advantage over the visitors.  As former U.N. ambassador, Bolton knows State as well as Mattis knows the Pentagon.

The president-elect several times referred to General Mattis as "Mad Dog" Mattis, which is Mattis's nickname.  Mattis also has a reputation as a "general's general."  Neither description applies to General Petraeus, despite his many accomplishments.  "Mad Dog" Romney?  I don't think so.  Mayor Giuliani capably led New York before and after 9/11 but is not tough or knowledgeable enough to stand up to State careerists.  Bolton wins again.

In July 2010, General Mattis replaced General Petraeus as commander of CENTCOM, a fact that may well lead to friction between the two four-stars.  How well they would get along in their new positions is a question mark.  Moreover, placing military officers in charge of the two most major policy organizations of our government might raise concerns that Trump wants the military rather than civilians to run the show.

State careerists would have a pretty easy time convincing Romney and Giuliani that they need to defend their turf against possible Pentagon "encroachment" by Mattis and his subordinates.  Rivalries would soon develop over many issues, some manageable like military personnel in embassies, others less easy to manage.  Bolton understands priorities and can be relied upon to avoid factionalism and get on with business.

Finally, not to be overlooked or downplayed is the "swelled head" factor. 

Mattis and Bolton are both humble men and would be able to assume the top positions at Defense and State without undergoing a transfusion of arrogance or pomposity.  I think Petraeus is safe on that score but is disqualified by other considerations.  I'm not sure about Giuliani, but being top diplomat would go to Romney's head pretty quickly.