With the defeat of the Tibetan army in Eastern Tibet in October 1950 and the signing of the Seventeen Point Agreement, the Chinese quickly built up a massive military force in Tibet and started an extensive road building program that within a few years linked Lhasa and the rest of Tibet effectively to China. They also built their first airport in Tibet in 1956. In and around Lhasa they built many military camps and installations and also intelligence and police offices. They requisitioned and purchased the large mansions of Tibetan aristocrats in central Lhasa for their many offices. All of these building were fortified and heavily defended before the March Uprising.