In 2009, I was nominated to be the 16th supreme allied commander of the North Atlantic Treaty Organization. While I had already served three years heading one of the military’s 11 combatant commands — U.S. Southern Command, focused on Latin America — this new job would be jumping into the deep end of the pool.

For starters, I would be the first Navy admiral to take the job — all my predecessors had been generals with deep experience in NATO. (My dream four-star job was thousands of miles away: commander of U.S. Pacific Command in Honolulu, a traditional posting for a Navy officer.) But Secretary of Defense Robert Gates wanted me in Europe, so off I went.

The other problem was that NATO was engaged in a brutal land war in Afghanistan, with nearly 150,000 troops hundreds of miles from the sea. I was worried about my ability to lead given the complexities of that coalition. When I relayed my doubts to both Gates and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, they both said, "Go talk to Colin.”