  We combine the six high-resolution Aquarius dark matter simulations with a
semi-analytic galaxy formation model to investigate the properties of the
satellites of Milky Way-like galaxies. We find good correspondence with the
observed luminosity function, luminosity-metallicity relation and radial
distribution of the Milky Way satellites. The star formation histories of the
dwarf galaxies in our model vary widely, in accordance with what is seen
observationally. Ram-pressure stripping of hot gas from the satellites leaves a
clear imprint of the environment on the characteristics of a dwarf galaxy. We
find that the fraction of satellites dominated by old populations of stars
matches observations well. However, the internal metallicity distributions of
the model satellites appear to be narrower than observed. This may indicate
limitations in our treatment of chemical enrichment, which is based on the
instantaneous recycling approximation. Our model works best if the dark matter
halo of the Milky Way has a mass of ~8 x 10^11 Msun, in agreement with the
lower estimates from observations. The galaxy that resembles the Milky Way the
most also has the best matching satellite luminosity function, although it does
not contain an object as bright as the SMC or LMC. Compared to other
semi-analytic models and abundance matching relations we find that central
galaxies reside in less massive haloes, but the halo mass-stellar mass relation
in our model is consistent both with hydrodynamical simulations and with recent
observations.
