I first assumed maybe his art collection was somehow inspired by the Titanic - but, I learned that he died in the Titanic sinking. He was a companion of Archibald b*** and was described as a "soldier of fortune." I'm not in position to comment on his objets d'art shown on the auction site..
Neither am I. I do know that there are works by him in several museums, including the MET, Smithsonian and Boston museum of fine arts. This one doesn't look to me to be among his finest works and so may sell quite reasonable. I do know that he was a winner of several war medals and according to at least one account was last seen helping women and children into the lifeboats.
Millet was a very capable painter of the chocolate box school. He tended to paint anything but contemporary America. Plenty of his work can be seen online but search for his full name or you'll get paintings by Jean-François Millet. An amusing example of his work is Between two Fires, which has nothing to do with the military.