Ford chassis brake lines

We lost our brakes on our 2004 Ford excursion while on Cape Cod about a year ago. I turned up the trailer brakes and drove to a campground. The front brakes would work if you stepped on the peddle far enough. Anyway, the steel line across the rear end had rusted out right at the clamp. I got the hose from the frame to rear end and the brake line and some fittings and fixed it at the campground. I had previously replaced the two front hoses and the line down the frame. I didn't see the spot under the clamp at that time.

I guess the OP is right, someone should look under your whatever every now and then.