Complex sentence: Aquilino Boyd was one of the first wave of civilian politicians to make peace with the military dictatorship (1968--1989) and who in his capacity as a diplomat and foreign minister played a key role in the negotiations that led to the 1977 Panama Canal Treaties.
Split into simpler sentences: Aquilino Boyd was one of the first wave of civilian politicians to make peace with the military dictatorship (1968--1989). In his capacity as a diplomat and foreign minister played a key role in the negotiations that led to the 1977 Panama Canal Treaties.