Why did the Titanic sink?

Late on 14 April 1912, RMS Titanic struck an iceberg in the North Atlantic while travelling at about 22 knots. The collision buckled plates and popped rivets along the starboard side, letting water into the first five or six watertight compartments; the ship could stay afloat with only up to four flooded. Because the bulkheads did not reach high enough, water spilled from one compartment into the next as the bow sank. The ship went down about 2 hours and 40 minutes after impact, early on 15 April. There were lifeboats for only about half of the roughly 2,200 people aboard, and more than 1,500 died.