The Germans stopped the pumps and opened the dikes, refilling the marsh with brackish water. They were being advised by the German malariologists Erich Martini and Ernst Rodenwaldt that the return of the salt water would encourage the return of "Anopheles labranchiae", which thrives in salty environments. The water would also destroy agriculture, removing essential supplies of food and fresh water from the vicinity, an act that had minimal military effect but devastated the population. Although it is true that the bog impeded movement of heavy equipment, the Germans did not flood the marsh for that reason; the equipment under heavy shelling from some of the largest artillery pieces the Germans had was going nowhere, anyway. The flooding was an act of biological warfare and was opposed by former Italian colleagues of the Germans in malariology, but someone on Kesselring's staff - unknown to this day - issued the order.