Songtham Somdet Phra Boromma Trailokanat Songtham ( full Thai title : สมเด็จพระเจ้าทรงธรรม ; RTGS : " Somdet Phra Chao Songtham " ) was the King of Ayutthaya from 1611 to 1628 of the House of Sukhōday . His reign was marked as prosperity after the First Fall of Ayutthaya and saw the commencement of trade with foreign nations especially the Dutch and the Japanese . Songtham filled his guards with foreign mercenaries most notably the Japanese – Yamada Nagamasa . Origin . Sources varied in Songtham ’ s origin . The " Royal Secretariat ’ s Chronicles " ( 1912 ) named him Prince Si Sin but other chronicles named him Prince Inthraracha . The prince was a minor prince born to Ekatotsarot with one of his concubines . As a minor prince , Inthraracha pursed religious ordination and became a respectful monk with the name Pimol Anantapreecha . Rebellion . Ekatotsarot died in 1610 , to be succeeded by incapable and one - eyed Si Saowaphak . Si Saowaphak ’ s weak rule gave opportunities for the nobility to usurp the throne . Here the " Royal Chronicles " told that Songtham ’ s adoptive son " Chameun " Sri Sorarak conspired a rebellion and marched to the palace in 1611 and held a ceremony for Sri Saowapak ’ s execution at Wat Kok Phraya . However , other chronicles said that it was Songtham ’ s younger brother Si Sin who did this . Nevertheless , as a popular religious prince , Songtham was given the Ayutthayan throne . Songtham appointed Sri Soralak the Uparaja but he died only a week after . Japanese . Not long after the coronation , in 1612 the Ayutthaya Palace was sacked by Japanese samurai who took the king away as a captive . Certain Siamese noblemen had cheated the Japanese merchants in trade agreements and their master " Ok Krom " Nai Wai ( a title for Japanese mercenary commander ) had been executed by the king in 1610 . King Songtham was attending a Buddhist audience when the Japanese stormed the palace . They called for the life of Siamese mandarins responsible for their vengeance . Songtham managed to calm the attackers down and sent them off the Menam valley but the Japanese rebels captured Phetchaburi so Songtham sent an army to pursue and suppress them . Religious viewpoints . Songtham was said to be very religious - both by the Siamese and van Vliet - as for his religious youth . His name Songtham was a posthumous reverence that means " maintaining the virtues " . His reign was the glamorous time for Siamese peasants who were free from wars and suppression . The most prominent achievement in his reign was the discovery of Buddha ' s Footprint at Saraburi . Songtham ordered the construction of a temple over the footprint - the footprint itself can still be seen today . From Songtham onwards , Ayutthayan kings paid annual respect to the Buddha ' s Footprint in a grand river procession . Martial affairs . On martial affairs , however , King Songhtam was less successful . In 1621 himself led Siamese armies into Cambodia to bring the kingdom under control but was repelled by King Sri Suriyopor of Oudong . Songtham sent his brother " Uparaja " Si Sin to invade again in 1622 and failed . Also in 1622 King Anaukpetlun of Pegu took Tavoy away from the Siamese . Siam . Songtham ' s reign was marked by the foreign activities in Siam . The Dutch and the Japanese ( with their Red seal ship s ) were the most frequent visitors who received the royal supports . Songtham sent four embassies ( about 20 people each ) to the Japanese Shogun in 1621 , 1623 , 1626 , 1629 , to Shogun Tokugawa Hidetada and Iemitsu . Dutch ship . In 1624 , Fernando de Silva led a Spanish fleet to sack a Dutch ship near the Siamese shoreline . This enraged Songtham who held the Dutch in great preference and ordered the attacks and seizures of all the Spaniards . The Portuguese , however , were treated alike and the Iberians were technically disgraced from Siam after nearly a hundred years of royal support .