Little-known European battle painting

[Segilla]

Apologies for this wispy question.

Many years ago a TV series about art showed a very large, portrait shaped, highly detailed oil painting of a battle, (from a museum in Austria?). It was said the picture was little-known, as was the battle, maybe.

[Kingaroo]

By portrait shaped, do you mean that the canvas was in the shape of a person's head or something?

[Segilla]

Sorry my meaning was not clear. Portrait = upright as opposed to landscape = sideways in computer printer language.