Which preposition to use with castelnau

in Occurrences 1%

Before the completion of the river road, about 1895, travelers from Cuzco to the lower Urubamba had a choice of two routes, one by way of the pass of Panticalla, followed by Captain Garcia in 1571, by General Miller in 1835, Castelnau in 1842, and Wiener in 1875; and one by way of the pass between Mts.

to Occurrences 1%

Where would be the sense of my writing you that the battle-front has settled down to uncomfortable trench work on the Aisne; that Manoury is holding the line in front of us from Compiègne to Soissons, with Castelnau to the north of him, with his left wing resting on the Somme; that Maud'huy was behind Albert; and that Rheims cathedral had been persistently and brutally shelled since September 18?

Which preposition to use with  castelnau