Mr. Denton, a Times photographer, and Mr. Gordon, a Times military correspondent, are with Kurdish forces near Sheikh Amir, Iraq, on the eastern approach to Mosul.

The Kurdish pesh merga forces started their advance by moonlight, in the early hours of Monday. East of the Islamic State-held city of Mosul, columns of tanks and trucks lumbered their way toward the objective: clearing villages of militants before any broader advance on the city could happen.

As day broke, the vehicles piled off the roads to avoid any improvised bombs and began moving across the dusty Nineveh plain toward the villages. The tank fire began, booming across the distance. Soon the crawl became a run.