In 1844, after studying sciences and law, Hammer settled in Solothurn as a lawyer and a notary, but he worked in Berlin, Zurich and Geneve too.

Elected president of the district court and 1856-68 as cantonal councillor of Solothurn, Hammer was soon regarded as leader of the old liberals and the opposition against the radical-liberal regiment of the Landammann Joseph Wilhelm Viktor Vigier von Steinbrugg.

Moreover, H., who was intent on compensation, played an important mediating role behind the scenes in the settlement of the Kulturkampf.

The portrait of Hammer was painted in 1889 by the Swiss-born American artist Adolfo Müller-Ury (1862–1947) and is signed Muller d'Uri.

It was reproduced on the cover of the dust-wrapper and as the frontispiece of Eduard Fischer's biography 'Bundesrat Bernhard Hammer und Seine Zeit', published in Solothurn in 1970.