It is the first time France's secondary heads have demonstrated. It is a measure of their exasperation at unfulfilled promises made by the outgoing education minister on the eve of the last election, and at the increasing stress of their job which leaves 652 posts unfulfilled.
But above all, it was a protest against being asked to carry legal responsibilities without the financial resources to meet them, and highlighted by seven cases before the courts. The most serious is a case of manslaughter.
Two weeks ago, the director and also the chief administrator of a lycee in one of Paris's most run-down suburbs - the Lycee Paul Eluard at Saint-Denis - were given a two-month suspended prison sentence following the death of a pupil in 1991; they must also pay 5,000 francs (Pounds 625) to the victim's family. The pupil was killed when a rusting basketball post fell on him. The director is appealing against the judgment, but the parents of the boy are seeking a stiffer sentence.
In a second case to have made the headlines, a pupil at a vocational lycee in Grenoble was left permanently disabled after his arm was caught in a machine which lacked part of its safety guard. The prosecution has asked for a 20,000-franc fine.
"We are sacrificial victims," says Marcel Peytavi, general secretary of the union which represents 75 per cent of secondary principals.
The union is demanding that legal obligations should be clarified and that financial recognition should be given for the increased responsibilities which come with a policy of greater autonomy in France's hitherto highly centralised education system.