Complex sentence: Nevertheless, Ferdinand of Aragon did not relinquish his long-cherished designs on Navarre, and married secondly Germana (Germaine of Foix), the daughter of Catherine's uncle who had attempted to claim Navarre over his deceased elder brother's under-age children.
Split into simpler sentences: Nevertheless, Ferdinand of Aragon did not relinquish his long-cherished designs on Navarre. For his second marriage, he married Germaine of Foix, the daughter of Catherine's uncle who had attempted to claim Navarre over his deceased elder brother's under-age children.