Complex sentence: Many Blacks were denied entry into regular units because of racism or distrust in British and Loyalist officers, so many joined the irregular Associators (also known as Refugees) where they often served in mixed-race units.
Split into simpler sentences: Many Blacks were denied entry into regular units because of racism or distrust in British and Loyalist officers. Many joined the irregular Associators (also known as Refugees), where they often served in mixed-race units.