Sailor of Fortune wrote, "I'm not talking about deploying the bow anchor. I'm talking about using bow windless to take strain from one or more stern anchors through block and tackle via a line fairled from aft to fwd to use windlass."
Ditto. I have used my windlass to kedge off just that way. Using the dinghy, I carried a stern anchor (a pretty big Danforth) out to deeper water, as far as the length of its rode would permit. Back at the stern of the boat, I fed the rode back aboard through an aft hawse hole in the starboard quarter. From there, I ran the line along the starboard walkway, past the pilothouse door, and up to the windlass. After heaving the line taut, doing my best to hand-set the stern anchor, I began taking the line in with the windlass. That was sufficient to move the boat stern first, and I was off the mud in a jiffy.
The boat was a 42' Grand Banks. In using the windlass to heave in on a line running aft, I feared chafe along the forward corner of the cabin trunk as the rode tightened and moved across the gelcoat, but there was no damage. A block attached to a breast cleat could have alleviated that concern, but I was working fast (against a falling tide) with the tools at hand.
Once I was free of the bottom, before trying to maneuver, I tied a fender to the end of the stern anchor rode and dropped it over the side. Once I had recovered the forward anchor (that had been set off the bow), I maneuvered back to pick up the stern hook. Mission accomplished.
How I got into that whole situation is another story . . .