Complex sentence: Vast quantities of gold, silver and valuable trade goods crossed the Atlantic in regular armed frigate convoys, funding the Spanish war effort and to intercept and seize these shipments the Royal Navy dispatched their own frigates to patrol the Spanish coast.
Split into simpler sentences: Vast quantities of gold, silver and valuable trade goods crossed the Atlantic in regular armed frigate convoys, funding the Spanish war effort. To intercept and seize these shipments the Royal Navy dispatched their own frigates to patrol the Spanish coast.