The Flashing Blade (French: Le Chevalier Tempête) is a French television serial made in the late 1960s. It was first broadcast in the UK on BBC children's television during the 1960s, with several re-runs throughout the 1970s. The British version of twelve 22 minutes episodes was created from the original four French 75-minute episodes.The fictional story is based upon historical events during the War of the Mantuan Succession (1628–1631) between France and Spain and its allies. Charles Emmanuel I, Duke of Savoy, a supporter of Spain, laid siege to Casale, the capital of Montferrat on the Savoie (Savoy) border. Despite numerous attempts to scale the defences, the beleaguered garrison held out. The Savoy army was eventually defeated by a French relief force on 18 March 1629.

The castle of Casale, seen being besieged in the opening credits, was filmed at Château Gaillard in France.