In an admittedly borderline “execution”, Louis de Bourbon, the Hugueunot Prince of Conde, was killed summarily at the end of the Battle of Jarnac on this date in 1569.
This nobleman’s conversion to Protestantism had been attended with the zeal so usual to that period. In the case of Conde (English Wikipedia link | French), that meant dipping his beak into some dramatic plotting.
Nothing daunted by its failure, he spearheaded the even riskier Surprise de Meaux, a design to seize not only King Charles IX but the rest of the royal family in 1567. This time, failure triggered a whole new installment of the on-again, off-again Wars of Religion.
The Year of Our Lord 1569 found Conde at the head of the principal Huguenot army in an extremely tense country. On March 13, that army met the Catholic force of Marshal Gaspard de Saulx at the Battle of Jarnac.*
The result was a smashing victory for the Catholics. As the disaster unfolded, Conde, wounded and alone, tried to offer his surrender to an enemy guardsman. He was instead shot on the spot — and his body borne back to Catholic lines for jeering.
* The teenage Walter Raleigh fought at this battle on the Huguenot side.