Operation MARKET-GARDEN was, in reality, two plans combined. MARKET envisioned dropping three and a half divisions of Lt. Gen. Lewis H. Brereton's First Allied Airborne Army near the Dutch towns of Eindhoven, Nijmegen, and Arnhem. The MARKET forces, under the command of Lt. Gen. F. A. M. Browning's 1st British Airborne Corps, consisted of the U.S. 101st and 82d Airborne Divisions and the 1st British Airborne Division, reinforced by the 1st Polish Parachute Brigade. The airborne soldiers would quickly seize the bridges over the canals and rivers between Eindhoven and Arnhem, thus opening a corridor for the ground, or GARDEN forces of the Second British Army. Lt. Gen. Brian G. Horrocks' 30 Corps would spearhead the ground exploitation, advancing from a bridgehead across the Meuse-Escaut Canal south of Eindhoven to the IJsselmeer River, over ninety miles to the north, in two to four days. Second Army's 8 and 12 Corps would make supporting attacks on Horrocks' flanks. If all went according to plan, the Allies would have a bridgehead over the Rhine at Arnhem before the fleeing Germans could establish a coherent defense.
MARKET-GARDEN was truly a daring proposition, with success hinging on three critical assumptions. First, 21 Army Group planners believed that the German defenses in the Eindhoven-Arnhem corridor were thinly manned by disorganized formations of 'low category' soldiers who would offer little resistance to the lightly armed airborne troops, much less to the rapid advance of the armored forces of 30 Corps. Second, the British presumed that the single narrow route suitable for armored vehicles could support the rapid advance of some 20,000 vehicles of the 30 Corps from their jumping-off point to Arnhem. Third, the plan banked on reinforcing and resupplying the airborne units by airdrops during a season when the weather in northeastern Europe rarely afforded good flying conditions. Nevertheless, the stakes of gaining a foothold over the Rhine and outflanking the Siegfried Line seemed to justify the gamble.
On 17 September, the roaring of thousands of engines from the airplanes of the vast Allied aerial armada supporting Operation MARKET-GARDEN shattered the calm of the clear skies over the Netherlands. Nearly 1,000 heavy bombers attacked German flak positions, while some 1,100 Allied fighters swept the skies searching for the Luftwaffe-all preparing the way for the 1,545 transport planes and 478 gliders of the largest airborne operation in history. In the early afternoon, over 20,000 airborne soldiers began landing on drop zones near Arnhem, Grave, and Veghel, while 30 Corps launched its attack toward Eindhoven.