In 1815, at the age of 21, Tereshchenko was drafted into the army and deployed to contest the Napoleonic invasion of Russia, finally ending up in Paris. His regiment was ordered to stay in apartments outside the French capital. For a few months, Tereshchenko and his fellow Cossacks lived near the town of Beauvais, where the fertile soil of the Bree valley produced beets just like those of his Ukrainian homeland. Tereshchenko took advantage of his stay by studying French.