  [abridged] We propose a tiered, UV--near-IR, cosmological broad- and
medium-band imaging and grism survey that covers ~10 deg^2 in two epochs to
m_AB=28, ~3 deg^2 in seven epochs to m_AB=28, and ~1 deg^2 in 20 epochs to
m_AB=30 mag. Such a survey is an essential complement to JWST surveys (<~0.1
deg^2 to m_AB<~31 mag at lambda>1100nm and z>~8). We aim to: (1) understand in
how galaxies formed from perturbations in the primordial density field by
studying faint Ly\alpha-emitting and Lyman-break galaxies at 5.5<~z<~8 and
trace the metal-enrichment of the IGM; (2) measure the evolution of the faint
end of the galaxy luminosity function (LF) from z~8 to z~0 by mapping the
ramp-up of PopII star formation, (dwarf) galaxy formation and assembly, and
hence, the objects that likely completed the H-reionization at z~6; (3)
directly study the lambda<91.2nm escape fractions of galaxies and weak AGN from
z~4.0--2.5, when the He reionization finished; (4) measure the mass- and
environment-dependent galaxy assembly process from z~5 to z~0, combining
accurate (sigma_z/(1+z) <~ 0.02) photo-z's with spatially resolved stellar
populations and kpc-scale structure for >~5x10^6 galaxies; (5) trace the
strongly epoch-dependent galaxy merger rate and constrain how Dark Energy
affected galaxy assembly and the growth of SMBHs; (6) study >~10^5 weak
AGN/feeding SMBHs in the faint-end of the QSO LF, over 10 deg^2 and measure how
the growth of SMBHs kept pace with galaxy assembly and spheroid growth, and how
this process was shaped by various feedback processes over cosmic times since
z~8. The proposed study is not feasible with current instrumentation but argues
for a wide-field (>~250 arcmin^2), high-resolution (<~0.02--0.11 [300--1700
nm]), UV--near-IR imaging facility on a 4m-class space observatory.
