Task: Question Understanding
Input (English): Passage: The failure of the Şarköy-Bulair operation and the deployment of the 2nd Serbian Army together with its much needed heavy siege artillery sealed Adrianople's fate. On 11 March after a two weeks' bombardment which destroyed many of the fortified structures around the city, the final assault started with Allied forces enjoying a crushing superiority over the Ottoman garrison. Under the command of General Nikola Ivanov, the Bulgarian 2nd Army with 106,425 men and two Serb divisions with 47,275 men conquered the city, with the Bulgarians suffering 8,093 and the Serbs 1,462 casualties. The Ottoman casualties for the entire Adrianople campaign reached 23,000 killed. The number of prisoners is less clear. The Ottoman Empire began the war with 61,250 men in the Adrianople fortress. Richard Hall notes that 60,000 men were captured. Adding to the 33,000 killed, the modern Turkish General Staff History notes that 28,500 man survived captivity leaving only 10,000 men unaccounted for as possibly captured . Bulgarian losses for the entire Adrianople campaign amounted to 7,682. This was the last and decisive battle that was necessary for a quick end to the war, even though it is speculated that the fortress would have fallen eventually due to starvation. The most important result was that now the Ottoman command lost all hopes of regaining the initiative, which made any further fighting pointless.
Question: Approximately when did the bombardment of Adrianople start?
Output (English): date