The Sixteen refers to the municipal government that was set up in Paris (in the city's sixteen districts) by extremists in the Holy League.
They sided with Spain against both Henri III and Henry IV and fanned the flames of fanaticism among the city's residents. They forced Henri III to flee Paris during the Day of the Barricades (May 1588) and held out against Henri IV's siege in 1590. In 1591, they hung three members of the Parlement – including First President Barnabé Brisson – whom they considered too moderate. Discredited and renounced by Mayenne, their influence waned and they were unable to oppose the king's entry into Paris in 1594. Those who had not fled were subsequently exiled.