Tā zài xiǎoshuō li yòng qiūbā lái fěngcì jūnfá de bīng.
In his novel he used the term qiuba to mock the warlords' troops.
Tips
memory
丘八 is a character-splitting joke: the character 兵 (bīng, soldier) can be visually decomposed into 丘 (qiū) on top and 八 (bā) on the bottom. Saying 丘八 is calling someone a soldier without using the word.
register
Derogatory and dated — common in late-Qing and Republican-era writing about warlord armies. Don't use it of modern soldiers; it would sound insulting and archaic.