 Complete the following phrase:  In the first half of the 13th century, settlements along the Daugava river were quite often attacked by the Lithuanians. The Livonian Order, which had begun conquering eastern Semigallia around the same period, made an alliance with the Semigallians and the Latgalians against the Lithuanians. In the winter of 1205, an army of Semigallians led by Viestards attacked the forces of Lithuanian Duke Žvelgaitis, who was returning from a war against Estonia with booty and Estonian slaves. His troops were caught unaware while crossing waist-high snowdrifts. Žvelgaitis was killed by a javelin thrown by the German Theodore Schilling. 1,200 Lithuanian knights perished; the Estonian slaves were slaughtered as well, in retribution for past crimes against the Livonians. In 1208, Viestards led a united Semigallian and crusader army into Lithuania but was defeated. In 1220, Mezuotne, the centre of eastern Semigallia was destroyed by the Livonian Order. In 1236, Semigallians participated in the decisive 