Why was the Declaration of Independence written ?

The Declaration of Independence was written mainly to persuade people that the Patriots’ cause was just and that the colonies deserved to be independent.  Thomas Jefferson and the others involved in writing and approving the Declaration wanted to persuade both foreign countries and American colonists of this idea.

Of course, one reason for the Declaration was simply to announce that the colonies were breaking away from the United Kingdom.  However, the document was meant much more to persuade than to inform.  If it had only been meant to inform, it would have been much shorter. Instead, the bulk of the Declaration is devoted to setting out the Americans’ complaints against the king and their philosophical justifications for rebelling.  All of this was meant to persuade.

The American leaders wanted to persuade both colonists and foreigners that the Patriots were in the right.  The leaders wanted and even needed to get foreigners on their side.  They hoped that foreign countries would recognize their independence and would perhaps pressure the British to let the colonies go.  If the colonists had to fight a war, they wanted foreign countries to help them fight that war. 

The leaders also wanted to persuade American colonists.  Not all colonists supported independence.  Scholars estimate that only about one-third of colonists were firmly in favor of independence while equal numbers were against independence and neutral.  The leaders of the independence movement wanted to get as many colonists as possible on their side so that they would have a better chance of defeating the British government.

Thus, the Declaration of Independence was written mainly to persuade colonists and foreigners to support the Patriots’ efforts to achieve independence.