In 1869 he took a doctorate at Göttingen with Ranke's pupil Georg Waitz, with a thesis on the government of Emperor Conrad II.

When Heinrich von Treitschke published his controversial writings against the Jews in 1879, Bresslau spoke openly and in a determined manner against his elder and senior professional colleagues, even though his position as extraordinary-professor had no permanent security.

[1] Nonetheless in 1878 Bresslau had worked together with Treitschke, a year before his anti-semitic contribution to the Prussian Annals, in an election-committee of the National-Liberal Party.

There he developed a thorough-going teaching and research programme and made himself a leading National-Liberal advocate for German identity.

His daughter was the medical missionary, nurse, social worker, and public health advocate Helene Bresslau Schweitzer.

On the model of the Monumenta Germaniae Historica and the Historical Commission of the Bavarian Academy of Sciences, the relevant source-material was sought out and usefully assembled for research.