DeSouza, early 1900's - Wash DC, anyone know of him?

A local buy/sell/trade shop has a huge photo of what appears to be about 500-600 WWI soldiers in front of (we think) the White House. The photo is 5'8" wide by about 12" tall. It's crazy wide. The uniforms, hats, and eyeglasses make me think it's from the WWI era. The signature says "Photo by DeSouza 467 PA Ave NW (Pennsylvania Ave) Washington DC".

It's heavily stained or water damaged, but it has really piqued my curiosity. Mostly I'm interested in the equipment used. I looked very closely at the image for quite a while, and it shows no evidence of being a multiple image. I can see no seam anywhere. The detail on the individual people is, IMO, amazing. I could find no movement in the image, not even in the trees, which makes me believe it was a somewhat fast shutter speed. Grain in the image was negligible, and I really didn't see any, so that makes me wonder how much this was enlarged.

I was thinking it was a panoramic stitch, but like I said, I can't see any evidence of that. Then I thought maybe one of those old pano cameras that the lens moves as the photo is being taken, but I would have imagined there would be some sign of a long exposure, wouldn't there be? Could it have been some crazy huge camera that has a negative that could be 6 feet wide? I know they're out there, but were they being used at that time?

If anyone has any guesses, I'd love to hear them. If you know anything about the photographer, I'd love to hear that to.

Cell phone snaps of the image (they're pretty crappy) -

It's probably made with a Cirkut camera. They were available in a variety of sizes, including a 12" tall roll format. I know someone who uses one today. The camera is mounted on a giant gear platter, and has a clockwork mechanism that you wind up and let the camera rotate. You can set the angle of rotation so that it only takes a few degrees, or you can let it go a full 360 degrees. If the photo were taken in full sunlight and no wind, you could well get shutter speeds that would yield everything tack sharp. Plus, with a 12" tall negative, it's a contact print so it will look sharper than it would if it were enlarged.

Awesome. I knew those cameras were out there, but couldn't remember the name. It's really amazing how crisp the image is from end to end. Thanks!