Although the name had been in use informally since 1453, in most contexts Istanbul was still Constantinople to non-Turks, and Kostantiniyye in most government contexts. After the fall of the Ottoman Empire and the formation of the modern Turkish Republic in 1923, the old name was gradually phased out.
The changeover was formalised on March 28, 1930, when the Turkish Postal Service Law came into force. All foreigners were requested to stop using the old names of Istanbul and various other Turkish locations. This was enforced by the post office’s refusal to deliver mail addressed to Constantinople, which drove acceptance of the new usage on pragmatic grounds.
Istanbul Not Constantinople – The Four Lads
Istanbul Not Constantinople – They Might Be Giants
The Dutch first built a settlement on Manhattan Island in 1613. It was the first European settlement on the island, located approximately at the site of the later World Trade Center complex. In 1623, the growth of the colony prompted the Dutch government to build a military post there, which was named Fort Amsterdam. The settlement grew even more, becoming known as New Amsterdam after the fort.
In 1664, the English opened the second Anglo-Dutch War by invading New Amsterdam on August 27. The official surrender of the colony took place on September 8, 1664, and the settlement and colony were renamed New York, in honour of James, brother to the English King, Charles II, and then the Duke of York. (He would later succeed his brother to the English throne, reigning from 1685 to 1688.)
Istanbul (not Constantinople) — The Four Lads
Istanbul (not Constantinople) — They Might Be Giants
History does not record whether it was so nice they named it twice on this date, or whether that came later.