Did the Buddha try to effect social change?

This month is Buddhist Action Month in the UK when we try to be a bit more socially engaged. To quote from the website > Despite Buddhism's reputation for stillness and withdrawal from the > world, UK Buddhists are engaged in a wide range of social-change > projects, alleviating suffering at home and abroad So leading on from this, I was wondering whether the Buddha promoted this kind of social engagement. Was the Buddha active in addressing political and social injustices of his time or did he more work within the social norms and bring about liberation in that way. I'm particularly interested in references to the Pali Canon to illustrate answers but answers from other traditions and texts would also be interesting.