This photographs shows Mennonite leaders from all over Russia who met in Moscow from Jan. 13-18, 1925. According to Gerhard Lohrenz, Heritage Remembered, p. 88, this conference has been nicknamed "the Second Martyrs Synod" because most of the men died in prison or exile during the 1930s.
First row: Franz Franz Martens, Heinrich K. Siemens, Franz Friesen, Bernhard Kornelius Baergen, Peter Klassen, David Heinrich Loewen. Second row: Johann Johann Peters, Gerhard Johann Lohrenz, Aron Aron Reimer, Johann Johann Martens, Peter P. Pauls, Johan Martin Janzen, Heinrich Epp, Gerhard Gaede, Peter Herman Friedrichsen. Third row: K. Nickel, Nikolai Franz Janzen, Peter Julius Siemens, David Penner, Hermann Hermann Rempel, Kornelius Loewen, Heinrich Voth, Kornelius Harder, Gerhard Heinrich Willms, Peter Peter Froese, Gerhard Jakob Derksen, Johann Johann Rahn, Abram Klassen, Abram Kornelius Neustaedter, Dietrich Wiens. Fourth row: Peter Heinrich Dick, Dietrich Heinrich Koop, Bernhard Wiens, D. Redekopp, Johann Gerhard Wiens, Aron Aron Dick, Alexander Heinrich Ediger, Jakob Aron Rempel, Abram Peter Willms, Jakob Heinrich Paetkau, Kornelius Kornelius Martens, Abram Aron Klassen, Jakob Abram Loewen, Johann Kliewer. Fifth row: Isaac Gerhard Krahn, Johann Bueckert, Peter P. Neufeld, Johann Siemens, Jakob Jakob Letkemann, Jakob Franz Huebert, Jakob Gerhard Wiens, Peter Peter Bergen, Daniel Braun, Jakob Toews, Abram Teichroeb, Johann Johann Wiebe, Heinrich Jakob Janzen, Aron Peter Toews. Sixth row: Johann Neufeld, David David Koop, Franz Johann Quiring, Johann Kornelius Martens, Julius Julius Pauls, David David Petkau, Kornelius Enns, Peter Schellenberg, Cornelius A. DeFehr, Jakob Kornelius Reimer, Kornelius Wiens, Jakob Goerzen, Kornelius Martens, Heinrich Unrau, Heinrich Abram Friesen, Nikolaj Friesen, P. Braun, Gerhard Kopper, Heinrich Jakob Martens.
This list of names is taken from the description of this photograph at https://chortitza.org/Pht/Konf.htm. It differs from Gerhard Lohrenz's listing on page 88 of "Heritage Remembered"