  We report on abundances of O, Mg, Si, Ca and Fe for 10 giants in the Sgr
dwarf spheroidal derived from high resolution spectra obtained with UVES at the
8.2m Kueyen-VLT telescope. The iron abundance spans the range -0.8 <[Fe/H] <
0.0 and the dominant population is relatively metal-rich with [Fe/H] -0.25. The
alpha/Fe ratios are slightly subsolar, even at the lowest observed
metallicities suggesting a slow or bursting star formation rate. From our
sample of 12 giants (including the two observed by Bonifacio et al 2000) we
conclude that a substantial metal rich population exists in Sgr, which
dominates the sample. The spectroscopic metallicities allow one to break the
age-metallicity degeneracy in the interpretation of the colour-magnitude
diagram (CMD). Comparison of isochrones of appropriate metallicity with the
observed CMD suggests an age of 1 Gyr or younger, for the dominant Sgr
population sampled by us. We argue that the observations support a star
formation that is triggered by the passage of Sgr through the Galactic disc,
both in Sgr and in the disc. This scenario has also the virtue of explaining
the mysterious ``bulge C stars'' as disc stars formed in this event. The
interaction of Sgr with the Milky Way is likely to have played a major role in
its evolution.
