Kuàngrìchíjiǔ de zhànzhēng ràng bǎixìng kǔbùkānyán.
The prolonged war left the common people suffering beyond words.
Tips
history
From 《战国策·赵策四》: 旷日持久,数岁,令士大夫余子之力,尽于沟垒 — describing how a military campaign stretched on for years and exhausted the soldiers. The classical sense of 旷 is 'to waste' time, not merely 'long'.
usage
Almost always negative — implies not just long but wastefully long. Common in legal, diplomatic, or war contexts. Compare to neutral 长期 (long-term).