Task: Text Simplification
Input (English): 1263 - the chieftains of the eastern part of iceland become the last to pledge fealty to the norwegian king , bringing a more complete end to the icelandic commonwealth and the icelandic civil war.
Output (English): in 1263 , chieftains of eastern iceland become the last to pledge loyalty to the norwegian king , bringing an end to the icelandic commonwealth and the icelandic civil war.