Complex sentence: In 2016, Kaepernick gained nationwide attention when he began protesting by not standing while the United States national anthem was being played before the start of games, motivated by what he viewed as the oppression of people of color in the United States.
Split into simpler sentences: In 2016, Kaepernick gained nationwide attention when he began protesting by not standing while the United States national anthem was being played before the start of games. This decision was motivated by what he viewed as the oppression of people of color in the United States.