A new generation of surveys has begun the collection of high-resolution spectra for millions of individual stars in the Milky-Way Galaxy. In the frameworks of the Gaia-ESO and HERMES surveys, international research teams will decipher the information and derive precise chemical abundances and stellar parameters with unprecedently large statistics. In a year’s time, the Gaia satellite will begin its mission to complement the data with stellar distances and kinematics. The knowledge of chemical compositions and ages of stars with enough statistics to sample the dynamics of the Galaxy will undoubtedly revolutionize our understanding of how it formed and evolved.The first part of the proposal is aimed at considerably improving the spectroscopic methods applied in large-scale surveys. A novel technique will be developed that models spectral line formation in non-local thermodynamic equilibrium in atmospheres computed with radiation-hydrodynamical convection simulations. Thereby, erroneous physical assumptions that bias almost all quantitative spectroscopy today will be removed so that automated analysis pipelines can determine both accurate and precise chemical abundances and stellar parameters for large samples. A successful outcome is secured by a careful calibration of the analysis methods on the Sun and other standard stars.The second part concerns the science exploration that will commence based on the superior information derived from the Gaia-ESO data. With the early universe in focus, a large sample of extremely metal-poor halo stars will be analysed and shed light on the formation and nucleosynthesis of the very first stars.This ambitious proposal ties together international expertise in atomic data calculations, stellar atmospheres, and chemical evolution modeling of our Galaxy, and directs the effort towards a common goal.