  We investigate the formation of infant globular cluster (GC) candidates in
high-resolution cosmological simulations from the First Billion Years (FiBY)
project. By analysing the evolution of the systems in the energy and angular
momentum plane, we identify the redshift at which the infant GCs first became
gravitationally bound, and we find evidence of radial infall of their gaseous
and stellar components. The collapse appears to be driven by internal
self-gravity, however, the initial trigger is sourced from the external
environment. The phase space behaviour of the infant GCs also allows us to
identify some characteristic groupings of objects. Such a classification based
on internal properties appears to be reflected in the formation environment: GC
candidates that belong to the same class are found in host galaxies of similar
morphology, with the majority of the infant GCs located in clumpy, irregular
proto-galaxies. Finally, through the inspection of two GC candidates that
contain only stars by z = 6, we find that supernova feedback is the main
physical mechanism behind their dearth of gas and that the systems subsequently
respond with an approximately adiabatic expansion. Such infant GC candidates
already resemble the GCs we currently observe in the local Universe.
