of the rebels during the Guo Huaiyi rebellion had expected Chenggong to come to their aid. Some company officials believed that the rebellion had been inciteded by Chenggong. A Jesuit priest told the Dutch that Chenggong was looking at Taiwan as a new base of operations. In 1654, he sent a letter to Taiwan to have a Dutch surgeon sent to Xiamen for medical assistance. In the spring of 1655 no silk junks arrived in Taiwan. Company officials suspected that this was caused by the Ming-Qing war but others felt it was a deliberate plan by Chenggong to cause them harm. The company sent a junk to Penghu to see whether Chenggong was preparing forces there but they found nothing. Defenses at Fort Zeelandia were strengthened. According to European and Chinese traders, Chenggong had 300,000 men and 3,000 junks. In 1655, the governor of Taiwan received a letter from Chenggong insulting the Dutch, calling them "more like animals than Christians," and referring to the Chinese in Taiwan as his subjects. He commanded them to stop trading with the Spanish. Chenggong sent a letter directly to the Chinese leaders in Taiwan, rather than Dutch authorities, stating that he would withhold his junks from trading in Taiwan if the Dutch would not guarantee his junks safety from Dutch depredations in Southeast Asia. To raise funds for his war effort, Chenggong had increased foreign trade by sending junks to Japan, Tonkin, Cambodia, Palembang, and Malaka. Batavia was wary of this competition and wrote that this would "undermine our profits." Batavia sent a small fleet to Southeast Asian ports to intercept Chenggong's junks. One junk was captured and its cargo of peppers confiscated but another junk managed to escape. The Dutch realized this would be received badly by Chenggong and thus offered an alliance with the Manchus in Beijing, however nothing came of the negotiations. The Taiwanese trade slowed and for several months in late 1655 and early 1656 not a single Chinese vessel arrived in Tayouan. Even low-cost goods grew scarce and as demand for them rose, the value of aboriginal products fell. Chinese merchants in Taiwan suffered because they could not take their products to China to sell. The system of selling Chinese merchants the right to trade in aboriginal villages fell apart as did many of the other revenue systems supporting the company's profits. On 9 July 1656, a junk flying