Original: He was sent into the military abroad to be away from her, and while gone, the girl suffered numerous misfortunes partly as a consequence of her unhappy marriage, finally dying penniless and disgraced, and with a natural (i.e., illegitimate) daughter, who becomes the ward of the Colonel.
Simplified: He was sent abroad to be away from her, and while gone, the girl suffered numerous misfortunes partly as a consequence of her unhappy marriage, finally dying penniless and disgraced, and with a natural daughter, who Colonel Brandon takes in.