This was undoubtedly the most tragic period in the history of the city, a period full of suffering and heroism. For everyone who lives in St. Petersburg the Blokada (the Siege) of Leningrad is an important part of the city's heritage and a painful memory for the population's older generations.

Less than two and a half months after the Soviet Union was attacked by Nazi Germany, German troops were already approaching Leningrad. The Red Army was outflanked and on September 8 1941 the Germans had fully encircled Leningrad and the siege began. The siege lasted for a total of 900 days, from September 8 1941 until January 27 1944. The city's almost 3 million civilians (including about 400,000 children) refused to surrender and endured rapidly increasing hardships in the encircled city. Food and fuel stocks were limited to a mere 1-2 month supply, public transport was not operational and by the winter of 1941-42 there was no heating, no water supply, almost no electricity and very little food. In January 1942 in the depths of an unusually cold winter, the city's food rations reached an all time low of only 125 grams (about 1/4 of a pound) of bread per person per day. In just two months, January and February of 1942, 200,000 people died in Leningrad of cold and starvation. Despite these tragic losses and the inhuman conditions the city's war industries still continued to work and the city did not surrender.

http://www.saint-petersburg.com/history/siege.asp