He was a leader of the French Radical Party and Minister of Finance, but his progressive views in opposition to the military alienated him from conservative elements.

After studying law and following lectures at the École des Sciences Politiques, he entered the civil service in 1888 as an inspector of finance, and spent most of his official career in Algiers.

The text submitted to Parliament provided for an annual declaration of their harvest by wine growers, prohibition of second-cycle sweetening, and control and taxation of purchases of sugar.

His advocacy of an income tax, and his uncertain and erratic championship of proletarian ideas, alarmed all the conservative elements in the country, and throughout the winter he was attacked with increasing vehemence from the platform and through the press.

In 1914, Le Figaro started the publication of love letters that had been sent by Caillaux to his second wife Henriette while he was still married to the first, Berthe Gueydan.

By the spring of 1917, he had become in the eyes of the public "l'homme de la défaite", the man who was willing to effect a compromise peace with Germany at the expense of Great Britain.

[6] On 10 July 1940, Caillaux voted as a Senator in favour of granting the cabinet presided by Marshal Philippe Pétain authority to draw up a new constitution, thereby effectively ending the French Third Republic and establishing Vichy France.