The Habsburg monarchy enacts a major redistribution…

The Spanish try to incorporate the Karankawa into their empire while the Karankawa engage in purely economic terms with the British and French, trading skins and deer for weapons (i.e., muskets, guns) and household goods.

Kamehameha tries again in 1803 to conquer the western Hawaiian Islands, but this time, disease breaks out among his warriors; Kamehameha himself falls ill, though he later recovers.

During this time, Kamehameha is amassing the largest armada Hawaiʻi has ever seen: foreign-built schooners and massive war canoes, armed with cannon and carrying his vast army.

Major breakthroughs in chemistry occur in 1803, with the identification of the elements rhodium and palladium (by William Hyde Wollaston); osmium and iridium (by Smithson Tennant); and cerium (by Wilhelm Hisinger, Jons Jakob Berzelius and Martin Heinrich Klaproth).

Another new earth, from the mineral later named gadolinite in Gadolin's honor, is reported independently in the literature in 1803 by several chemists, including Martin Heinrich Klaproth and, working together, Jöns Jakob Berzelius, and Wilhelm Hisinger.

The asteroid Ceres, which had just been discovered two years before, lends its name, as ceria, to the newly obtained earth.

Researchers refer to yttria and ceria as the rare earths, because they have been discovered in a rare mineral, and closely resemble other known earths.

The elements of which yttria and ceria were the oxides then receive the names yttrium and cerium, respectively.

Napoleon claims Northern Italy in 1803.

In the ensuing peace, France keeps its gains and Germany reorganizes its states.

Sa'ud's father is assassinated in 1803, soon after the return of his son from the capture of Mecca, by a Shi'ite in the mosque of Ad-Dir'iyah in revenge for the desecration of Karbala'.

India’s population is two hundred million by 1803.

Arthur Wellesley, the French-trained younger brother of Governor-General Richard Wellesley, breaks the power of the Marathas at Assaye in 1803.

Mahmud sues for peace after Shoja' occupies the capital in 1803, and Shah Shoja' ascends the Afghan throne.

The 1803 treaty of Amiens restores Dutch control over the Cape.