The Duke of Wellington
1812-1814
oil on mahogany panel, 64.3 cm x 52.4 cm
263/8" x 20 5/8"
National Gallery London

"...Wellington insisted on taking the portrait with him on his campaign in the north of Spain, and the picture was framed while still wet, in a frame that was too small. The resulting damage meant that a year or two later he sent it back to Goya for corrections. In addition, depicting the medals and honours that Wellington had accumulated throughout the campaign set Goya an arduous task: the scarlet jacket is thickly encrusted with painted corrections as the artist tried valiently to keep up with their number and type. Eventually, however, the portrait ended up with the wrong medals and an incorrect uniform, and Goya subsequently made a drawing of Wellignton as a vain peacock." From Sarah Symmons book Goya, Phaidon Press, 1998, page 249.

The National Gallery in London has
a page on this painting here.