One year after Kelsier's death Straff Venture arrives with an approximatly 50,000 men strong army before the gates of Luthadel. Two days later Lord Ashweather Cett arrives with an almost just as strong army. The Siege begins.
The two initial armies take control of the canals and cut off all incoming resources in to Luthadel. This also causes the citizens in Luthadel forbidden to leave by the King. Although the forbidden to leave, citizens were able to leave though secret tunnels and passages around the city.