Menachem Mendel Auerbach succeeded his grandfather as A.B.D. Krotoschin after the death of R. Menachem Mendel Margolith in 1729.

He was known as the Younger.

He was leader of the Council of the Four Lands, married the daughter of R. Isaac, Parnas of Posen and Krotoschin, son of E. Samuel Katzenellenbogen, who according to family tradition, helped to finance the destitute Swedish King Charles X11, after his Russian defteat, so that he could reach home.

He wrote approbations to Shtei HaLechem in 1733, Even HaShoham, Me'irat Einayim and Or Chachamim by R Benjamin, son of R. Saul Katzenellenbogen A.B.D. Samter and Krotoschin.

He died in 1760 and left responsa and manuscripts extant.

Source

The Unbroken Chain, by Neil Rosenstein (1990) Volume 11, p 819, G8.2