Apart from the effects on Qin's military, Shang Yang's reforms also increased labour for numerous public works projects aimed at boosting agriculture, and made it possible for Qin to maintain and supply an active military force of more than a million troops. This feat could not be accomplished by any other state, except Chu, during that time. Qin's conquests of the southern states of Ba and Shu in present-day Sichuan province also provided Qin with major strategic advantages. The lands in the new territories were very fertile, and helped serve as a "backyard" for supplies and additional manpower. It was hard for Qin's rivals to attack Ba and Shu, since the territories were located deep in the mountains upstream of the Yangtze River. At the same time, Qin's strategic position in Ba and Shu provided it with a platform for launching attacks on the Chu state, which lies downstream of the Yangtze.