  We present the first all-sky view of the Sagittarius (Sgr) dwarf galaxy
mapped by M giant star tracers detected in the complete Two Micron All-Sky
Survey (2MASS). The main body is fit with a King profile of 30 deg limiting
radius, but with a break in the density profile from stars in tidal tails. We
argue that much of the observed structure beyond the 224' core radius may be
unbound as the satellite undergoes catastrophic disruption. A striking, >150
deg trailing tidal tail extends from the Sgr center and arcs across the South
Galactic Hemisphere. A prominent leading debris arm extends from the Sgr center
northward of the Galactic plane to an ~40 kpc apoGalacticon, loops towards the
North Galactic Cap (NGC) and descends back towards the Galactic plane,
foreshortened and covering the NGC. The Sgr tails lie along a well-defined
orbital plane that shows little precession, which supports the notion of a
nearly spherical Galactic potential. The Sun lies near the path of leading Sgr
debris; thus, former Sgr stars may be near or in the solar neighborhood. The
number of M giants in the Sgr tails is >15% that within the King limiting
radius of the Sgr center. That several gigayear old M giants are so widespread
along the Sgr tidal arms not only places limits on the dynamical age of these
arms but poses a timing problem that bears on the recent binding energy of the
Sgr core and that is naturally explained by recent and catastrophic mass loss.
Sgr appears to contribute >75% of the high latitude, halo M giants; no evidence
for M giant tidal debris from the Magellanic Clouds is found. Generally good
correspondence is found between the M giant, all-sky map of the Sgr system and
all previously published detections of potential Sgr debris with the exception
of Sgr carbon stars -- which must be subluminous to resolve the discrepancy.
