Eisenhower's decision on 7 September to forgo the capture and development of the ports of Brittany, except for the ongoing Battle for Brest, in favour of an advance to the German border. This left the Americans wholly dependent upon the increasingly distant port of Cherbourg and Normandy beaches. With the rehabilitation of the railways and construction of pipelines unable to keep up with the pace of the advance, American logistics in the Northern France campaign depended on motor transport. Yet even before Operation Cobra began, there was a shortage of trucks, especially of the large semi-trailers that were especially suitable for long-distance haulage. Expedients like the Red Ball Express came at a high price. Tyres and other parts wore out, and vehicles were run without proper maintenance. Dry batteries, lack of oil, and loose nuts and bolts caused breakdowns. Driver fatigue was another important factor; round trips sometimes went for 48 to 65 hours. By the end of September, 5,750 vehicles required major repairs.