The operation began with a major air strike involving more than 200 aircraft against three airbases, Hawk SAM batteries, three command centers, artillery positions and several radar stations, employing MiG-21s, MiG-17s, and Su-7s. This was in concert with artillery strikes starting at 14:05 from nearly 2,000 pieces against the Bar-Lev line, and against armor concentration areas and artillery positions, using field guns, howitzers, mortars, tank guns, B-10 and B-11 recoilless rifles. The self-propelled 152 mm howitzers and 130 mm field guns were assigned counter-battery fire missions against Israeli artillery. The 53-minute-long fire preparation, one of the largest in history, was divided into four barrages. The first, fifteen minutes long, was aimed at enemy targets on the eastern bank up to a depth of 1.5 kilometers. An estimated 10,500 shells were fired against Israeli targets in the first minute alone.