Complex sentence: In 2009, two members of the Council of Elders resigned--then-president Clyde Kilough, whose resignation was effective July 28th, 2009; and Richard Thompson, effective July 27th, 2009.
Split into simpler sentences: In 2009, two members of the Council of Elders resigned. This included then-president Clyde Kilough, whose resignation was effective July 28th, 2009; and Richard Thompson, effective July 27th, 2009.