Wiktionary
comble
n. (context heraldiccharge English) A band along the top part of the shield, half the breadth of the chief.
Usage examples of "comble".
Our destination this time was Combles, and we took over a battery position from the French, who politely made us acquainted with our new surroundings.
Yet correspondents knew that readers at the breakfast table would be hungry for details about Combles, where the taking of the Schwaben Redoubt or Regina Trench, which were defended savagely, had no meaning.
Rancourt was the other side of Combles, which explains the plum simile.