In February of 1944, air forces of the Allied powers accidentally bombed Nijmegen, killing about 800 people and destroying the train station and much of the inner city.
In 1985 the Dutch War Studies Commission determined that indeed the bombardment of Nijmegen (and, on the same day, of Enchede, Deventer, and Arnhem) was not intentional. A principal reference for their conclusion was the book "De Fatale Aanval," published in (?) by Alfons Brinkhuis, an amateur historian.
The events of February 22 were the misbegotten result of a plan called "Operation Argument."
Operation Argument was an immensely complicated logistic scheme, the largest Allied air operation to date intent on the total destruction of German military air capability.
Aside from the massive complexity of the movement of hundreds of bombers, the necessary weather conditions were specific, meaning that the plan was contingent upon a state of affairs dictating a specific date on short notice.
The Americans had developed a logistic of flight that enabled large-scale bombardment of targets, the whole group overflying a destination within a short period.
The British method, used previously, involved the overflight of targets in the formation of a queue of bombers. This method of bombardment, clearly simpler to organize, had its main disadvantage in the obvious vulnerability of easy targeting and in the long period of notice for enemy gunners.
In the American sytem, battle groups formed around the element of three airplanes one in lead and middle; another behind, to the right and above; and another behind, to the left and below. Four groups of these, and three groups of those groups, flew together 36 bombers in formation, appearing from below to be nearly wingtip-to-wingtip. Their passage over any target or hazard would me momentary.
But organization and movement of any such formation would have to be difficult in ideal circumstances which was not how things were on the 22nd of February, 1944.
The weather conditions required by Operation Argument were that England would be covered by a deck of clouds, and that the skies over Germany would be clear. Clouds over England, from where flights would originate, would obscure the formation until it was across the English Channel and clear German skies would allow visual targeting.
In order to form the battle groups, individual planes departed a given airfield, one or two every minute depending on conditions, and rise in a great circle around a vertical radio beam which coordinated their arrangement "in place." This battle group would then depart for a second position above another vertical radio beam, where the group would form position relative to another battle group and in this way organize the pattern for onward movement, into territory where the radio contact would be strategically limited.
Over Germany, each battle group had its descending list of objectives, targets arranged by priority. If a battle group were unable to achieve the primary target, then it was to attempt the second-in-priority. If the second were unachievable, and the third, then a battle group was to attack a "target of opportunity."
On that February afternoon in 1944, several Dutch cities became accidental targets of opportunity for battle groups returning from an unsuccessful mission over Nazi Germany.