Marines with Dog Company, 1st Battalion, 7th Marine Regiment, patrol through the swirling dust during Operation Sangin United Horizons, May 19. Operation Sangin United Horizons was a large-scale operation, which took place May 17 through 20. Dog Company, 1st Bn., 7th Marines, was responsible for finding and destroying weapons caches, improvised explosive devices and drug producing facilities. - Marines with Dog Company, 1st Battalion, 7th Marine Regiment, patrol through the swirling dust during Operation Sangin United Horizons, May 19. Operation Sangin United Horizons was a large-scale operation, which took place May 17 through 20. Dog Company, 1st Bn., 7th Marines, was responsible for finding and destroying weapons caches, improvised explosive devices and drug producing facilities.