At 0520 British Summer Time on the morning of 15 September 1916, a new epoch in the history of warfare began, as forty-nine “machine gun destroyers” belonging to a battalion of the British Army’s Machine Gun Corps (Heavy Branch) left their assembly areas opposite Courcelette, Martinpuich, and Flers. Or so the story has gone ever since, and doubtless will during the current centennial. Granting that mechanized warfare had to start somewhere, any useful assessment must include proportions, and if we include those proportions — especially the number of tanks involved and the degree of success achieved, the birth of what my former instructors at the Armor School called “The Combat Arm of Decision” does not look all that auspicious. Indeed, what we commonly see as a precursor of Guderian’s Sichelschnitt, Rybalko’s Kutuzov, Patton’s breakout, Sharon’s Gazelle and Schwarzkopf’s Desert Storm provides us with textbook examples of how not to prepare and execute any military operation let alone how not to employ armor. In the tank’s Great War baptism of fire, 16 of the 49 did not make it from the assembly area to their attack positions, becoming lost, ditched, or having thrown a track before joining the battle that they had been expected to decide. Of the 33 that crossed the line of departure, 17 either ditched or suffered mechanical failure before making contact, 6 were knocked out or damaged by enemy fire without reaching their objectives, 1 ran low on fuel in no man’s land and returned to British lines, and 1 got so lost that it wandered into another division’s sector. Rumbling forward at three and a half miles per hour, the remaining eight suppressed enough Bavarian infantry during the advance to make an impression; one tank caused enough panic among defenders of a strongpointed factory to aid in a significant haul of prisoners and another shot up an enemy battery. While the maximum gain of two miles with a haul of 400 prisoners came as a welcome tactical success to the division commanders involved, it was no more a strategically significant breakthrough than the bloodbath of 1 July had been.