Crossing the Front Line is a firsthand account of international peace monitoring in a modern war zone. Drawing on multiple deployments to eastern Ukraine between 2014 and 2018, retired Canadian police officer William "Bill" Kelly recounts life and duty along active front lines as a member of the OSCE Special Monitoring Mission. Through patrols under fire, tense negotiations at checkpoints, and long drives through shattered villages, Kelly offers an unfiltered view of what it means to observe, document, and report violence while trying to reduce escalation. He describes the constant balance between professional neutrality and private emotion, the pressure of writing precise reports under stress, and the uneasy awareness that a single misunderstanding can endanger lives. The narrative moves beyond headlines and geopolitics to focus on the human realities of war: families living without heat or security, communities divided by fear, and the quiet courage that persists in ordinary people. Kelly also reflects on camaraderie within multinational teams, the mental toll of repeated exposure to danger, and the lasting impact of witnessing suffering at close range. More than a military or political analysis, this memoir is a reflection on service, humanity, and purpose, an honest record of what it feels like to stand between opposing sides, do the job with integrity, and carry those experiences home.