The Polish-Lithuanian hetman Jan Karol Chodkiewicz, while resting his forces in Birże (Biržai), learned of Swedish deployments from Pärnu (present day Estonia) moving towards Daugavgrīva (in present day Latvia) and set out to cut these off. However the Swedish units managed to enter Daugavgrīva before Chodkiewicz's arrival and as a result the hetman turned back and moved towards Pärnu, hoping to take the defenders there under command of Daniel von Wochen by surprise. Chodkiewicz's forces arrived on February 28, 1609 but when his troops tried to creep up to the city's walls unnoticed the Swedish garrison fired their cannons which established that a surprise attack was not going to work.