Battle of Qicheng (921) — the same event in Old History of the Five Dynasties and New History of the Five Dynasties

Old History of the Five Dynasties: Li Siyuan charged with three thousand iron cavalry, and the Liang army was routed, with twenty thousand captured…

What each source says

Old History of the Five Dynasties (Jiu Wudai shi), Annals · AD 921 · 戚城

Li Siyuan charged with three thousand iron cavalry, and the Liang army was routed, with twenty thousand captured or killed.

梁軍愈恐,步兵漸至,李嗣源以鐵騎三千乘之,梁軍大敗,俘斬二萬計。
Location: 舊五代史 卷29

New History of the Five Dynasties (Xin Wudai shi), Annals · AD 921 · 戚城

Dai Siyuan was defeated by Jin forces at Qicheng.

冬十月,思遠及晉人戰于戚城,敗績。
Location: 新五代史 卷03 龍德1年10月

Place: 濮陽

Show on the map — open Old History of the Five Dynasties (Jiu Wudai shi), Annals