The Bảo Đại Thông Bảo was a round Copper-alloy coin with a square hole produced by the Nguyễn dynasty under French protection and was the last cash coin produced both in Vietnam and the world, this ended a long series of cast Vietnamese coinage that started with the Thái Bình Hưng Bảo in 970. The cast Bảo Đại Thông Bảo were produced at the Thanh Hóa Mint, while the machine-struck variants were produced in Hanoi by the colonial French government. These coins bear the name of Emperor Bảo Đại who ascended the throne in 1926 but continued the production of the earlier Khải Định Thông Bảo that bore his father's name until 1933 when he ordered the production of new coins with his reign name, which was normal as previous Vietnamese emperors also kept producing cash coins with the inscription of their predecessors for a period of time. The cast smaller Bảo Đại Thông Bảo cash coins with blank reverses were only valued at piastre. The Bảo Đại Thông Bảo were probably cast into 1941 or 1942 and the production was stopped because the occupying Japanese forces wanted the copper and were acquiring all of the cash coins they could find and stockpiling them in Haiphong for shipment to Japan for the production of war materials. Cash coins would continue to circulateofficially in the Democratic Republic of Vietnam until 1948 with an official exchange rate set of 20 cash coins for 1 đồng.
Machine-struck Bảo Đại Thông Bảo coins
The Frenchsimultaneously began minting brass machine-struck cash coins in Hanoi, with the same inscription as the cast Bảo Đại Thông Bảo cash coins, that weighed 1.36 grams and had an official exchange rate of piastre, but were probably only valued at piastre. These coins were being minted at the Hanoi Mint because the French had cut the funding for producing cast cash coins at the Thanh Hòa Mint which meant that the Protectorate of Annam wasn't producing enough cast cash coins to satisfy the demands of the Vietnamese markets for these low value coins for every day exchange. The machine-struck Bảo Đại Thông Bảo cash coins were designed by René Mercier. There were two variants of this cash coins where one had a large version of the Chinese "大" while the other had a smaller "大". After the Japanese had forced the production of Bảo Đại Thông Bảo coins because they were commandeering all copper in Vietnam new sapèque-like coins made from zinc were created in Hanoi and by the Japan Mint in Osaka to replace these coins as the copper was being used for the production of Japanese weaponry and other military equipment, though the coins from Osaka didn't make it to the Vietnamese market as the shipping of war supplies was deemed more important by the Japanese government. There were a total of 98,000,000 machine-struck Bảo Đại Thông Bảo sapèques produced.
