Question

why had the dignitaries and the world leaders gathered there​

Answer 1

All gathered there to celebrate the new democratic Nation

Answer 2

The dignitaries and the world leaders gathered there​ to congratulate and acknowledge the oath-taking ceremony of the newly democratic nation of South Africa.

• The line has been taken from the story Nelson Mandela: Long Walk to Freedom. The international leaders and the dignitaries were present at the prestigious ceremony where the first Black President of South Africa, Nelson Mandela was going to address the nation and give his first speech to the citizens of South Africa.
  
• The leaders across the globe for the first time present to congratulate the President as well as the citizens of South Africa for their newly found freedom, and peace, and greeted them with respect.
  
• The presence of such dignified leaders created a strong international foundation of global acceptance and recognition of the effort of South Africa as an independent nation and this in turn ended the policy of apartheid.

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