I sat watching the rain on the train window - silver threads weaving erratically over the cold, wet glass. I could see my reflection there too, flitting over the darkening English countryside - the pale blur of my face with its heavy, somber brows and dark sunken eyes underscored by purple bruises of exhaustion, and the line of my mouth tense with the strain of the last few months. The tracks of the raindrops were superimposed across it like tears, and I thought how fitting that was in light of all that had happened.

My mind drifted back over the last eight years, virtually all of them overseas. Seven of...