2 sentences for 孤军奋战 (gū​jūn​fèn​zhàn)

1. 在没有任何援军的情况下，这支部队依然在孤军奋战。

   zài méi​yǒu rèn​hé yuán​jūn de qíng​kuàng xià, zhè zhī bù​duì yī​rán zài gū​jūn​fèn​zhàn.

   This unit continues to fight alone without any reinforcements.

   Source: Dong Chinese Dictionary

2. 他在这家公司里孤军奋战，独自完成了整个项目的开发。

   tā zài zhè jiā gōng​sī lǐ gū​jūn​fèn​zhàn, dú​zì wán​chéng le zhěng​gè xiàng​mù de kāi​fā.

   He fought a lone battle in this company, completing the entire project development by himself.

   Source: Dong Chinese Dictionary