The date of the introduction of sugar into Cuba is uncertain. Different authorities place it anywhere from shortly after the discovery of the island in 1492 to 1580. Von Humboldt is silent on the point, but says that Cuba did not participate in the sugar industry to any extent in the sixteenth century, so that its importance in that respect belongs to a later period.[48] Up to 1772 sugar cultivation was greatly hampered by restrictions of the Spanish government; after that date special privileges were canceled and the right to grow sugar was given to all Spaniards. This naturally encouraged production, which from 4390 tons in 1760 increased to 14,000 tons in 1790. The revolution which destroyed the sugar plantations and mills of Santo Domingo in 1791 stimulated the development in Cuba still further. During the ten years that followed, the number of mills increased from 473 to 870, and by 1802 the output of sugar reached 40,800 tons. In those days mills were very small, crude affairs and were worked by oxen. Cuba, in common with all sugar-raising countries, felt the effects of the European wars very severely, but her sugar trade revived after the overthrow of Napoleon and the resumption of commerce through normal channels. With increased production the question of labor became a serious one. The number of slaves on the island had been sufficient as long as the sugar crop was limited, but with expansion came the need for more African negroes, so in 1834 the governor, Miguél Tacon, caused many new slaves to be brought in. He did much to help the industry in other directions, particularly by suppressing abuses, and under his administration the planters enjoyed prosperity such as had never been known. Fresh lands were brought under cultivation and the shipping ports grew in importance and activity. While figures showing the annual production of Cuba were tabulated, beginning with 1850, their accuracy was open to question until 1882, in which year an export duty was imposed, and the records kept by the authorities from that time forward are reasonably correct. Nevertheless, it is known beyond any doubt that 610,000 tons were produced in 1870 from 1200 small mills. The first war with Spain (1868-78) and the abolition of slavery worked havoc with the industry. All children born of slaves were proclaimed free in 1872 and slavery was entirely abolished in 1880, without any indemnification to the slave owners. Sugar producers found freeman labor both costly and hard to obtain, the island was ravaged by fire and sword, and in the markets of the world beet-root sugar, protected by bounties, was proving a powerful competitor. These were dark days for the planter.