  Mergers of and interactions between galaxies imprint a wide diversity of
morphological, dynamical, and chemical characteristics in stellar halos and
tidal streams. Measuring these characteristics elucidates aspects of the
progenitors of the galaxies we observe today. The M81 group is the perfect
galaxy group to understand the past, present, and future of a group of galaxies
in the process of merging. Here we measure the end of star formation (t$_{90}$)
and metallicity ([M/H]) of the stellar halo of M82 and the eastern tidal stream
of NGC 3077 to: 1) test the idea that M82 possesses a genuine stellar halo,
formed before any interaction with M81, 2) determine if NGC 3077's tidal
disruption is related to the star formation history in its tails, and 3) create
a timeline of the assembly history of the central trio in the M81 group. We
argue that M82 possesses a genuine, metal poor ([M/H] ~ -1.62 dex) stellar
halo, formed from the merger of a small satellite galaxy roughly 6.6 Gyr ago.
We also find that the stars present in NGC 3077's tails formed before tidal
disruption with M81, and possesses a roughly uniform metallicity as shown in
Okamoto et. al. 2023 implying that NGC 3077's progenitor had significant
population gradients. Finally, we present a timeline of the central trio's
merger/interaction history.
