I seem to be on a roll this morning, posting from my "to post" folder.
I did a "Photograph Nature for 7 Days" thing that was going round on FB earlier this summer. These are ferns held up to the sun. (The pink is my fingers.)
Prepare for a battle or adopt a warlike stance.
In times of war or siege, Italian families would vacate their homes and rent apartments in safer areas. In order to protect themselves they would hire soldiers to sleep on the floor in shifts.
Ordinarily we would want to verify such stories before publishing them here as part of a phrase derivation. In this case though it isn't really important. The phrase wasn't well known outside of the USA and Italy prior to the Godfather movies. It was used there, and later in The Sopranos television series, to mean 'preparing for battle'. Whether or not the stories that originated it are true doesn't alter the fact that the screenwriters of those films used them in that context.