The Iraqis, realising that the Iranians were planning to attack, decided to preempt them with Operation al-Fawz al-'Azim (Supreme Success) on 19 March. Using a large number of tanks, helicopters, and fighter jets, they attacked the Iranian buildup around the Roghabiyeh pass. Though Saddam and his generals assumed they had succeeded, in reality the Iranian forces remained fully intact. The Iranians had concentrated much of their forces by bringing them directly from the cities and towns throughout Iran via trains, buses, and private cars. The concentration of forces did not resemble a traditional military buildup, and although the Iraqis detected a population buildup near the front, they failed to realize that this was an attacking force. As a result, Saddam's army was unprepared for the Iranian offensives to come.