Lacking the heavy weapons to destroy the Japanese bunkers directly, Zhang Zhizhong decided to encircle them instead. On August 16, he ordered his men to take the streets surrounding the Japanese strongholds. Every time a street was successfully cleared, the Chinese would set up a sandbag blockade, gradually surrounding each stronghold and closing off all possible routes of escape. The tactic was successful at first and the Chinese were able to destroy many emplacements and outposts in a single day. However, the Japanese then deployed tanks in the broad streets, enabling them to easily repel Chinese attacks and defeat the encircling strategy. On August 18 the Chinese attack was called off.