The speech „I have a dream“ was given by Martin Luther King in front of the Lincoln Memorial (Washington DC) on August 28, 1963 – 100 years after Emancipation Proclamation.
It was given to all dark-skinned people an the revealing Negro-Organisations.
With “I have a dream” Martin Luther King wants do commemorate the Emancipation Proclamation, which was made to set the slaves free (ll. 1-12) and the fulfilment of the promises of the Declaration of Independence (ll. 13-17). So he innumerates the demands of dark-skinned people (ll. 53-62).
Another purpose is to show the discrepancy between promises and the prevailing situation and to strengthen the wish and belief of the dark-skinned, that one day they will achieve their goals (e.g. ll. 69-72).
But he also wants to convince his audience that a non-violent way is the better tactic to achieve these goals. King is indeed critical of competitive civil right organisations, but he tries tu engage them positively in order to achieve unity an to demonstrate it to the outside world (ll. 41-52).