Brainchild of British Field Marshall Bernard Montgomery, Operation Market Garden was a aggressive plan to end World War II in Europe by Christmas 1944. It used paratroopers to capture key bridges ("Market") and tanks ("Garden") to spearhead the ground assault.
In a nutshell: Due to a series of mishaps, however, the mission failed to capture the main "prize" objective — the bridge at Arnhem. The mission ended after nine days of gallant fighting by the Allies including British, American, and Polish forces. An oversimplification, to be sure, but the mission is thoroughly documented in the definitive book on the subject, Cornelius Ryan's superb A Bridge Too Far.
For the anniversary of the operation, we've got six special missions that reward Consumables, Garage Slots, and Flag Emblems for Belgium and the Netherlands — locations where the actual operation took place.
Note: You can only complete the missions and earn rewards for Allied Forces or German Forces, but not both.