A groundbreaking new account of Britain’s military strategy from 1914 to 1945—spanning both World Wars and the turbulent interwar years—this book offers a comprehensive analysis of how Britain navigated one of the most intense and consequential periods in modern history.

Though separated by just two decades, the two global conflicts demanded radically different strategic responses. How did Britain adapt its military planning between and during these wars? And how were high-level decisions shaped by the complex interplay between political leaders and military commanders?

For the first time in a single volume, this history examines both world wars together, shedding light on the often tense and evolving relationship between civilian politicians and the armed forces. Drawing on a wealth of previously unexplored material from both military and political archives, Conquer We Must reveals how leaders such as David Lloyd George and Winston Churchill sought to steer military operations—Lloyd George’s bold interventions in First World War tactics, and Churchill’s relentless, often contentious negotiations with Allied leaders during the Second.

Yet, as this compelling narrative shows, while politicians aimed to control strategy, their influence over the actual conduct of war by the army, navy, and air force remained limited. The result is a nuanced and revealing portrait of power, decision-making, and the enduring challenges of civil-military relations in times of total war.