Complex sentence: It was during this sojourn that he married and started a family (see below), and to improving his estates by inviting Protestant farmers to take up tenancies while keeping on Roman Catholic tenants who had proved loyal to his family during the rebellion.
Split into simpler sentences: It was during this sojourn that he married and started a family (see below). He worked to improve his estates by inviting Protestant farmers to take up tenancies while retaining Roman Catholic tenants who had proved loyal to his family during the rebellion.