How to understand this paragraph, which recruits from Mandela’s Lessons in Leadership?

How to understand this paragraph, which recruits from Mandela’s Lessons in Leadership?

Leadership effectiveness is situational. A leader’s unique skills and attributes must match the moment. In the case of Mandela’s visionary leadership, this match was excellent.
Notice, for example, that Mandela’s decision to rely on nonviolence and to campaign for democracy and equality in the new South Africa was based, in part, on the specific political and social circumstances he faced. Even in the apartheid era, the South African government maintained a strong tradition (derived from its European heritage) of respect for certain democratic norms, including elections, effective checks and balances, and a strong, independent system of justice. Mandela and his African supporters were able to appeal to these institutions and to the values they represented as a way of rallying open-minded white South Africans to their cause. Furthermore, it is important to mention that in the person of F.W. d e Klerk, South Africa’s last leader under the apartheid regime, Mandela found a negotiation partner who shared his vision of a peaceful transition and showed the courage to help carry it through. The two men subsequently shared