 The final blow to Panama's shrinking control of the transit trade between Latin America and Spain came before the mid-18th century.As a provision of the Treaty of Utrecht at the end of the War of the Spanish Succession in 1713, Britain secured the right to supply African slaves to the Spanish colonies (4,800 a year for 30 years) and also to send 1 ship a year to Portobelo.The slave trade provision evidently satisfied both countries, but the trade in goods did not.