This was a great adventure series out of France that appeared during the Canadian Broadcasting Corporation "after-school" kid's TV series, "Razzle Dazzle". Thierry was not only an unmatched sling man, but the savvy leader of a band of French rebels during the Hundred Year War.
Jean-Claude Drouot portrayed Thierry of Janville, who begins the series as a young lord betrayed out of his title and property by conniving steward, Florent, played by Jean-Claude Deret. Actress Celine Leger played his love interest, Isabelle. Joined by his friends, Thierry becomes a "Robin Hood" type of character and fights undercover to end the iron rule of the ruthless Brits.
I remember the adventure was top-notch and very watchable. Thierry La Fronde was unique in that it portrayed the English as the bad guys and the French as the heroes. In Canada, we were used to English television portraying the Brits and the Yanks as the heroes. The dialogue was often hard to follow because, being dubbed into English, the lip movements often didn't match the spoken words.
I hope this isn't giving anything away, but the last episode had the most disappointing ending I can ever recall seeing on TV and I hope to one day see the series again to see if things really turned out the way I remembered.