It is not the Red over the White but the Blue ( the better name is the Cornflower Blue) over the White. The banderole wasn't the marking of a branch of service but of an unit. In the case it is of the 4th Niemen Uhlan Regiment that was a cavalry unit. The regiment garrisoned in Vilnius city (Lithuania). In September 1939 the regiment belonged to Wilenska Cavalry Brigade.
Here you are the colourized variant of the image.
