Second of May 1808 (El dos de mayo de 1808) (sketch 1)

In this first sketch Goya focused on the figures in the foreground, leaving those of the middle ground and the buildings in the background very roughly sketched and in the shadows. The outlines are created with strong black marks, and the colours used are vivid, less toned down than in the definitive work. Some of the hues used here are also different. The blue trousers of the Valencian figure who leaps at the enemy's horse on the left-hand side of the composition is swapped for the white of the sash in the final version, making it less striking. The change means that the painter makes the red of the Mameluke's trousers the focus of the viewer's attention.

There are other alterations, such as the position of the head of the dead soldier on the left, which is portrayed in a much more gruesome way in the canvas, since he no longer wears a hat, and is placed with his face towards us so that we can see his lifeless face and his slit throat. The other changes made favour the realism and the stark brutality of the scene, meaning that the final piece is an impressive, shocking testimony, the poses and gestures of the figures made more furious and threatening.

The support is unusual, a way round the scarcity of materials - and in particular, canvas - suffered by the artist during the war years. Eighteen works on panel by Goya are preserved from this period, and some of these have been found to have underlying paintings. Goya also had to reuse canvasses to get by, as revealed by x-rays carried out of some pieces.