资料题：The phrase" in high gear" in Pangraph3, sentence 1 is closest in meaning to（  ）。

The military aspect of the United States Civil War has always attracted the most attention from scholars.The roar of gunfire, the massed movements of uniformed men, the shrill of bugles, and the drama of hand-to-hand combat have fascinated students of warfare for a century.Behind the lines, however, life was less spectacular.It was the story of back-breaking labor to provide the fighting men with food and arms, of nerve-tingling uncertainty about the course of national events, of heartbreak over sons or brothers or husbands lost in battle.If the men on the firing line won the victories, the means to those victories were forged on the home front.Never in the nation's history had Americans worked harder for victory than in the Civil War.Northerners and Southerners alike threw themselves into the task of supplying their respective armies.Both governments made tremendous demands upon civilians and, in general, received willing cooperation.By 1863 the Northern war economy was rumbling along in high gear.Everything from steamboats to shovels was needed and produced.Denied Southern cotton, textile mills turned to wool for blankets and uniforms.Hides by the hundreds of thousands were turned into shoes andharness and saddles, ironworks manufactured locomotives, ordnance, armor plate.Where private enterprise lagged, the government set u its own factories or arsenals.Agriculture boomed, with machinery doing the job of farm workers dawn into the army.In short, everything that a nation needed to fight a modem war was produced in uncountednumbers.Inevitably there were profiteers with gold-headed canes and flamboyant diamond stickpins, but for every crooked tycoon there were thousands of ordinary citizens living on fixed incomes who did their best to cope with rising prices and still make a contribution to the war effort.Those who could bought war bonds; others kitted, sewed, nursed, or lent any other assistance in their power.