Completed as an oil on canvas, an inventory of paintings in 1701 showed it would have hung in the Royal Hunting Lodge, Torre de la Parada, on the outskirts of Madrid.
Rather than depict Mars as the usual virile, Roman God of War, Velazquez has chosen to show Mars as an ordinary, older man. Mars is seated on a bed, his pose mirrors those of certain statues such as Michelangelo's Il Pensieroso and Ludovisi Ares, a Roman copy of the Greek statue of the God of War. Yet this Mars sits forward, which emphasises his sagging skin and that his once muscled body is no longer as strong as it was.
His face is slightly shadowed by the overly large helmet he wears but the viewer can see his impressive moustache which would have been a sign of valour in Spain at that time. His nakedness is covered by the rather luxurious drapes of the bedding. Mars holds his staff but the rest of his armour, his shield and sword seem to have been abandoned carelessly on the floor. Mars gazes out towards the viewer but rather than admiration, the viewer feels a sense of sadness or pity for him.
It is not known if Velazquez painted this image using a live model but he certainly manages to capture a sense of realism. His focus on the anatomy and diffused outlines, coupled with the filmy haze he creates, gives life to his figure. Velazquez was apparently experimenting with techniques and he used very finely ground pigments and heavily diluted oils to created the effects in this painting.
Velazquez had shown a lack of reverence for classical mythological figures before in some of his other paintings and he clearly chose to paint this image of Mars as an almost tragic-comedic character. Some historians have suggested that in "Mars Resting", Velazquez has depicted Spain's declining military power at the time. Other writers have suggested that this image is of the God having just bedded Vulcan's wife Venus.
Whether there was a deliberate meaning in the painting or it was simply to entertain and amuse King Philip IV of Spain, "Mars Resting" is a wonderful painting that the viewer can admire and contemplate for hours.