In times of revolution, beware of the first head that falls. It whets the people’s appetite.

[En temps de révolution, prenez garde à la première tête qui tombe. Elle met le peuple en appétit.]

Victor Hugo (1802–1885) French writer, journalist, human rights activist, politician

Last Day of a Condemned Man [Le Dernier Jour d’un Condamné], 1832 Preface (1829) [tr. Woolen (1992)]
    (Source)

(Source (French)). Other translations:

In times of revolution, take care for the first head which falls, -- it whets the appetite of the people!
[tr. Reynolds (1840)]

In revolutionary times, beware of the first execution. It excites the sanguinary passions of the mob.
[tr. Fleetwood (1840)]

At the time of a revolution, look out for the first head that falls. It whets the people's appetite.
[tr. Ward (1896)]

During any revolution beware the first head that rolls. It gives the people an appetite.
[tr. Moncrieff (2009)]