Khmer–Cham wars

Tensions between the Khmer Empire and Champa reached a climax in the middle of the 12th century when both deployed field armies and waged devastating wars against each other.

In 1132, he persuaded Cham king Jaya Indravarman III to join forces with him to attack Đại Việt, where they briefly seized Nghệ An and pillaged the coastal districts of Thanh Hoá.

[7] After a failed attempt to seize seaports in southern Đại Việt, Suryavarman turned to invade Champa in 1145 and sacked Vijaya, ending the reign of Jaya Indravarman III and destroying the temples at Mỹ Sơn.

Another stronger Khmer army also suffered the same wretchedness fate at the battles of Virapura (present-day Nha Trang) and Caklyaṅ.

[13] After securing peace with Đại Việt in 1170, Cham forces under Jaya Indravarman IV invaded the Khmer Empire over land with inconclusive results.

[14][15][16] Multiple-bow siege crossbows were introduced to Champa from Song dynasty in 1171, and later were mounted on the backs of Cham and Vietnamese war elephants.

Vidyanandana defeated the Chams, and proceeded to occupy Vijaya and captured Jaya Indravarman IV, whom he sent back to Angkor as a prisoner.

The Khmer later also had double bow crossbows mounted on elephants, which Michel Jacq Hergoualc’h suggest were elements of Cham mercenaries in Jayavarman VII's army.

[22] A Cham renegade-Prince ong Dhanapatigräma, overthrew and expelled his ruling nephew Vidyanandana/Suryavarman to Dai Viet, completing the Khmer conquest of Champa.

[12] From 1203 to 1220, Champa as a Khmer province was ruled by a puppet government led by either ong Dhanapatigräma and then prince Angsaräja, son of Harivarman I, who would later become Jaya Paramesvaravarman II.