He was beheaded on the Grand-Place/Grote Markt (Brussels' main square) because of his resistance to innovations in city government detrimental to the power of the guilds and for his suspected involvement with uprisings within the Austrian Netherlands.
In 1716 the Austrians raised new taxes on the Flemish and Brabantine cities to fund the Dutch occupational forces installed by the Barrier Treaty and questioned their old medieval privileges.
The Italian Marquess de Prié, deputy for the absent governor-general, Prince Eugene of Savoy, suppressed the riots with brute force.
In the same year, the newly elected deans of the Guilds of Brussels were to swear to uphold the law, including a supplementary rider to the liberties of the city imposed in 1700.
Frans Anneessens was seen as the most important of these and was lured to a business conference with an Austrian colonel to discuss victuals for his regiment.
As the government feared trouble they had forced the priests to remove the ropes of the church bells and all major streets and squares were occupied by Austrian soldiery.