This is the scene corresponding to the phrase of 'Bensei-shukushuku yoru kawawo wataru' (crossing a river in the night, making even horse-whipping sound smaller) in "Kawanakajima," a Chinese poem composed by Sanyo RAI.
これが、頼山陽の漢詩『川中島』の一節、「鞭声粛々夜河を渡る」（べんせいしゅくしゅく、よるかわをわたる）の場面である。