Goguryeo Strikes Liaoxi
King Yeongyang led some 10,000 Malgal troops in a pre-emptive attack on Sui’s Liaoxi; Emperor Wen’s counter-invasion of 300,000 failed.

Yan Li-pen · Public domain · Source
Sui, having reunified China in 589, demanded submission from its neighbours, and Goguryeo trained troops and stored grain in readiness. In 598 King Yeongyang struck first, leading some 10,000 Malgal troops into Liaoxi west of the Liao River, but was beaten back by Wei Chong, the Sui commander at Yingzhou.
Emperor Wen sent his son Yang Liang, Prince of Han, with 300,000 men by land and sea. The army was ravaged by rain and disease and the fleet by storms; eight or nine in ten died. Yeongyang sent envoys with a formal apology and the fighting stopped — until Emperor Yang’s great invasion of 612.