Combine venison, wine, carrots, celery root, onion, juniper, and bay leaves in a large bowl. Marinate refrigerated at least 8 hours.
Remove venison, patting dry, and reserve the marinade with its vegetables.
Heat oil in a large pot over medium-high heat. Brown venison in batches. Set aside.
Add the marinade vegetables to the pot and cook 6–8 minutes until softened.
Return venison to the pot along with the marinade liquid and broth.
Bring to a simmer, cover, and braise 2 hours until fork-tender.
Season with salt and pepper. Strain the sauce if a smoother finish is desired, pressing the vegetables through.
Serve venison with the sauce spooned generously over the top.