Initially, when the British military learned that the Chimera were advancing onto London, the base, with 94,000 troops inside it was sealed to prevent Crawlers from entering and infecting the entire base. However, with many troops and personnel inside, it only meant that the Chimera would try to break in through very high tactical means. Eventually many soldiers were killed, and some left the base trying to get to other command posts or trying to fight the Chimera outside the base. By October 1950 only about 14,200 soldiers remained in the base and the Chimera penetrated the base from below using Burrowers loaded with Slipskulls. British personnel repelled the first assault. A week later on October 14th, the Chimera burrowed in again, this time from the River Thames, thereby flooding the base, killing 14,000 soldiers. Of the 200 soldiers who survived, many were then lured into the water by Sirens and were killed. Some, however, managed to escape into London.