Artillery of the Nguyễn lords

Between 1627 and 1672, seven campaigns were waged by the Trịnh in an attempt to break the Nguyễn, without success, along a front line near the 17th parallel, which later divided North and South Vietnam, from 1954 to 1975.

The Nguyễn were much weaker than the Trịnh in terms of having an established state and administration, with a vastly smaller army and population from which to draw resources, but their fortification system and their superior artillery allowed them to repel attacks from a stronger enemy while at the same time pushing southwards in the Nam tiến ("southward march") which established Vietnam's modern-day territory.

The court records assert that the Mạc's fortifications were quickly crushed when Nguyễn Hoàng employed "large cannons of all types" in battle.

At the time, Chinese traders had difficulty obtaining artillery, so scholars pinpointed Macau, then an important Portuguese trading port, as the most likely source of the cannons.

[2] In his diary, the Vietnamese-speaking Jesuit priest Christoforo Borri, a Catholic missionary in Vietnam in the 1620s, asserted an unconventional hypothesis to explain the Nguyễn cannons.

He claimed that Nguyễn Phúc Nguyên's decision to flout the authority of the Trịnh was prompted by the fortuitous acquisition of the cannon, writing that his defiance was caused by being "suddenly furnished with divers pieces of artillery recovered and gotten out of the ship-wreck of sundry ships of the Portugals and Hollanders."

Early 20th century French-language scholars such as Le Thanh Khoi, Charles Maybon and Leopold Cadiere presumed that a Portuguese man by the name of Joao da Cruz had started a foundry in 1615.

In another account, the Tien Bien recorded that in 1631, a cannon foundry existed in a quarter of Huế known as Phuong Duc, where da Cruz was later reported to have worked.

This led the historian Anthony Reid to opine that the Nguyễn had begun to view their artillery only for decorative purposes, as was the case in other Southeast Asian countries, as "more a means of boosting morale and expressing the supernatural power of the state than of destroying the enemy".

[4] Ironically, their adversary, the Tây Sơn army was heavily armed with firearms of all sorts, from primitive hand cannon called "hỏa hổ" (fire tiger) to flintlock and field guns.