When US Air Force officer John Boyd returned home from running a military base in the Thai jungle in 1974, the US war machine was being driven from Vietnam. Boyd reasoned that plucky underdogs outmaneuvering great powers was not inevitable. What if, the burgeoning strategist asked, the American military could cut dead weight — and learn to be as nimble as any Viet Cong guerrilla?

Answering this question has defined the career of Dominic Cummings, Britain’s controversial political operative who, this Wednesday, carried out an extended public mauling of his former master Boris Johnson. Cummings presents himself as Westminster’s Boyd — a scrapper, a varied thinker, a bull tearing through both the enemy and his own army’s bureaucracy. This synthesis of dominance, insurgency, and maneuver defined both his Brexit campaign and his 2019 election bid, which saw a radical Labour program beaten because a party that had already ruled for almost a decade convinced people it represented a greater break with the status quo.

When Cummings got his Boyd moment — his chance to savage the generals and princes of his own Pentagon — it made for grim, gripping television. In a seven-hour parliamentary committee hearing, he laid tens of thousands of deaths at the doorstep of the administration he had helped lead and showed uncharacteristic humility in doing so. He outlined the preventable failure of state systems, from health to social care to national security and procurement. He castigated not just Johnson but ministers, civil servants, and most of the people and institutions in British public life. He also aired a theory of what went wrong; but what he didn’t say is as important as what he did.