A visual summary of the Milky Way’s early assembly. Left: at early times, the Milky Way was dominated by a hot disk of high-α stars (red), with some metal-poor stars in the halo (blue) and some low-α stars in the disk (orange). Middle: the merger at z ≈ 1 populated most of the halo with the accreted metal-poor stars, but also heated some in situ high-α stars to halo-like orbits. Right: following the merger, only the low-α disk continues to grow, fueled by gas accreted during the merger.