[2][3] The Dutch East India Company (VOC) had conflicted with Nguyen-ruled Cochinchina (southern Dai Viet) since 1641 because of their alliance with Trinh lords in the north who was fighting in a civil war against their rivals, the Nguyen clan in the south.

[4] In 1639 Trịnh Tráng sent his envoys to van Diemen's VOC base in Batavia, sought for establish a military alliance with the Company in exchange for trading privileges for the Dutch in his Tonkin domain.

[7][8] In late May 1642 five VOC warships with 222 men led by Jan van Linga raided central Vietnam coast possessed by the Nguyen domain, burned houses, seized civilians as hostages, before heading north to join with Trinh army.

50 Dutch prisoners along with captain Joris Welten were allowed to sail back to Java on 19 May 1643 on a junk, but two days later a Portuguese warship attacked the junk, killed 32 Dutchmen,[11] 14 able to survive, and only one made way back to Batavia.1 In January 1643, five VOC warships with 290 soldiers and sailors from Formosa, led by general Johannes Lamotius, arrived at Tonkin, expected to join with the Trinh army to attack Cochinchina later that year, however after five days, the Dutch withdrew and left one ship to support the Trinh, after acknowledged that the lord was not eager to launch the campaign during spring season.

The Trinh regime fell into internal strife as two frustrated brothers of Trịnh Tạc fought against him in a succession conflict that turned into bloody mobs through the streets of Hanoi in 1645 after the military withdrawal of the Dutch.