The purpose was obvious: draw two lines across Italy, from coast to coast, and stop all rail traffic between them. One line ran through Pisa to Rimini, and the other was south of Rome. Strategic, tactical and coastal air forces were turned loose, each with assigned missions.

There was a different concept to the attacks this time. When the fighting was in southern Italy, attacks on the marshalling yards were the best use of air power tactically, because most of the supplies headed for the battle area passed through only a few major yards. In central and northern Italy, the industrial heart of the country, there were too many yards to keep knocked out of action.

Bombing statistics from earlier interdiction strikes against railroads showed that it took more than 400 tons of bombs to put the average yard out of action, but less than half that would destroy a bridge. Further, it was easier to lay track and repair yards than it was to rebuild or replace a bridge. And every important rail line had bridges them by the dozen, often in isolated regions and with little opportunity to bypass them either with the temporary construction of another rail line, or with a road.

In two ways, this was a new approach to the use of tactical air power. First, it used fighter-bombers extensively, and tested their abilities to prepare the way for a ground offensive. Second, previous interdiction strikes had been against a class of targets, such as bridges or marshalling yards. Now the target was a transportation system, whole segments of railroads. with their yards, bridges, tunnels, maintenance and repair shops, and rolling stock. With that out of action, the fighter-bombers could turn to the roads, finding and destroying the vehicles that the Germans would certainly use to replace their lost rail transportation. Another target was coastal shipping which, small effort though it was, still moved some supplies.