"I fully realize," he wrote, "that it has been largely due to your assistance that the enemy is checked.... I consider your work in the line to be greatly enhanced by the fact that for six weeks previous to taking your place in the front line your men had been working at such a high pressure erecting a heavy bridge over the Somme. My best congratulations and warm thanks to you all." It appeared that a gap had to be stopped in the bending line through which the Germans otherwise would have streamed. Amiens lay before their advancing hosts, and the way was open. The critical moment came on the afternoon of Tuesday, March 26, 1918. It was imperative that more troops should be thrown into the British line to arrest the German onrush. Reenforcements were on the way, but could not arrive in time. A dashing British officer, Brigadier General Carey, hastily improvised a scratch force of every available element within reach. American engineers were among them, and they were eagerly drawn into the fray. By telephone, messenger, and flag signals, General Carey assembled a little army from behind the lines which included labor battalions, cooks, and orderlies, sturdy middle-aged men, of various occupations, electricians, signalers, members of an infantry training school, machine gunners hurriedly armed with rifles, engineers, and fifty cavalrymen for scouting. He also improvised a staff as he proceeded, "officers learning the ground," as one onlooker described it, "by having to defend it and every man from enlisted man to brigadier jumping at each job as it came along." Early in the German advance, British reports had mentioned "Americans fighting shoulder to shoulder with the French and British." No American force was then identified as in the fight, and not until several days after did Pershing begin to send reenforcements to the Allies. The Americans referred to so mysteriously were part of that strangely mixed force that Carey drummed up from the void. These engineers at Carey's call picked up rifles and merged themselves in his motley corps without orders from anybody. They had been called from their work, which was constructing and operating field railways and building bridges. The beginning of their exploits was due to three companies of an American engineer regiment being caught in the early bombardment. Ordered to fall back, one of the companies, which had been consolidated with the British Royal Engineers, was delegated to the task of guaranteeing the destruction of the engineers' dump referred to by General Pershing, which it had been decided to abandon. This detachment destroyed all the material, made a rapid retreat, caught up with the larger group, and immediately resumed work, laying out trenches. These operations lasted from March 22 to 27, 1918. As the German attack became more intense, the engineers joined up with the mixed force General Carey had assembled.