Spanish forces, sometimes accompanied by native allies, led expeditions to conquer territory or quell rebellions through the colonial era. Notable Amerindian revolts in sporadically populated northern New Spain include the Chichimeca War (1576–1606), Tepehuán Revolt (1616–1620), and the Pueblo Revolt (1680), the Tzeltal Rebellion of 1712 was a regional Maya revolt.  Most rebellions were small-scale and local, posing no major threat to the ruling elites.  To protect Mexico from the attacks of English, French, and Dutch pirates and protect the Crown's monopoly of revenue, only two ports were open to foreign trade—Veracruz on the Atlantic and Acapulco on the Pacific. Among the best-known pirate attacks are the 1663 Sack of Campeche and 1683 Attack on Veracruz.  Of greater concern to the crown was of foreign invasion, especially after Britain seized in 1762 the Spanish ports of Havana, Cuba and Manila, the Philippines in the Seven Years' War. It created a standing military, increased coastal fortifications, and expanded the northern presidios and missions into Alta California. The volatility of the urban poor in Mexico City was evident in the 1692 riot in the Zócalo. The riot over the price of maize escalated to a full-scale attack on the seats of power, with the viceregal palace and the archbishop's residence attacked by the mob.