As pagodas could help obtain a better distant view, naturally army commanders wanted to use them as observation towers for watching enemy maneuvers. In ancient times there were no such things as balloons, airplanes or satellites as means of reconnaissance, so hills, trees and other tall objects were used for observation purposes or as beacon towers. But hills and trees were not to be found everywhere, and observation towers and defense works were not tall enough for such purposes. Pagodas, therefore, which were not only tall but also good hiding and resting places, became the ideal substitutes for observation towers and defense works. For instant, Liaodi Pagoda (Pagoda for Watching the Enemy), located in today's Dingxian County, Hebei Province, was built as a military observation tower, though it was supposed a Buddhist pagoda containing the relics of saints. At the time the pagoda was built the place was located on the border between the Northern Song Dynasty (960-1127) and the Liao Dynasty (916-1125). Because military conflicts often took place there, the commanders of the Northern Song Dynasty decided to build a pagoda in Kaiyuan Temple in Dingzhou to be used as an observation tower. In order to make a display of ceremony, Emperor Zhenzong (998-1022) of the Northern Song Dynasty issued a special decree for its construction. In name, of course, the pagoda was built for worshipping Buddhism, but we have learned from the stone tablets still kept in the pagoda that most contributors to the construction were military commanders or officers stationed on the border at that time. It took more than fifty years (1001-55) to build the pagoda, and when it was finished, no one even attempted to hide its true purpose by giving it a more religious-sounding name. In order to serve its military purpose, the pagoda was built to the maximum height engineering technology could reach, at that time. Standing eighty-four meters high, it is the tallest ancient pagoda still existing in China.
Yingzhou (today's Yingxian County) in Shanxi Province was also located on the border between the Northern Song and Liao Dynasties. It was a base of the famous generals of the Yang family who served the Northern Song Dynasty loyalty and often made surprise attacks on Liao troops. A wooden pagoda at Yingxian County today was once used by the Liao Dynasty to observe Song troops' maneuvers but it was called by a Buddhist name the Sakyamuni Pagoda.
Many ancient pagodas served military purposes. In Yulin, Shaanxi Province, one of nine towns of strategic importance and headquarters of the commander-in-chief of the defense troops of that area along the defense line of the Great Wall during the Ming Dynasty (1368-1644), there was a Lingxiao Pagoda built on top of a hill. Because of its high position the pagoda was also used as an observation tower by the defense troops. In order to make shooting and hiding more convenient, the inner structure of the pagoda, including doors and windows, was designed in the same way as defense fortifications. Xisi Pagoda in Yinchuan, Ningxia Hui Autonomous Region, similarly served military purposes during wartime. In Chinese history many other ancient pagodas made important contributions by serving as observation towers and defense works.