The Battle of Kokenhausen (Kokenhuza, Latvian: Koknese) was a major battle opening the Polish–Swedish War (1600–1611). It took place on the 13 June (O.S.) or 23 June (N.S.) 1601 near Koknese (in Baltic German Kokenhausen) in Livonia (now in Latvia). In the battle, Polish forces defeated the Swedish relief force and captured the besieging force, relieving the Polish garrison. The battle is notable as one of the greatest victories of the Polish hussars, who defeated their numerically superior Swedish adversaries.