Blanc was a French journalist, historian (Histoire de la Révolution Française, 1847) and socialist thinker (l'Organisation du travail, 1839). He was a member of the Provisional Government of the Second Republic (1848), and a deputy (1848; 1871-82). He had to go into exile after the June Days Uprising, and lived in London until the fall of Napoleon III (1870). He was a close friend of Victor Hugo during the exile.
The four first letters were bought from Andrieux on 26 March 1964 for 225 francs.