The Battle of Rudau (German: Schlacht bei Rudau, Lithuanian: Rdavos mis) was a medieval pitched battle fought between the Teutonic Knights and the Grand Duchy of Lithuania on 17 or 18 February 1370 near Rudau village, north of Knigsberg (now Melnikovo village in the Kaliningrad oblast). According to the Teutonic chronicler Wigand of Marburg and the Livonian chronicle of Hermann de Wartberge, the Lithuanians suffered a great defeat.

The Northern Crusades or Baltic Crusades were Christian colonization and Christianization campaigns undertaken by Catholic Christian military orders and kingdoms, primarily against the pagan Baltic, Finnic and West Slavic peoples around the southern and eastern shores of the Baltic Sea, and to a lesser extent also against Orthodox Christian Slavs (East Slavs).

The most notable campaigns were the Livonian and Prussian crusades. Some of these wars were called crusades during the Middle Ages, but others, including most of the Swedish ones, were first dubbed crusades by 19th-century romantic nationalist historians. However, crusades against Estonians, but also against 'other pagans in those parts' were authorized by Pope Alexander III in the bull Non parum animus noster, in 1171 or 1172.