  We present four ab initio axisymmetric core-collapse supernova simulations
for 12, 15, 20, and 25 $M_\odot$ progenitors. All of the simulations yield
explosions and have been evolved for at least 1.2 seconds after core bounce and
1 second after material first becomes unbound. Simulations were computed with
our Chimera code employing spectral neutrino transport, special and general
relativistic transport effects, and state-of-the-art neutrino interactions.
Continuing the evolution beyond 1 second allows explosions to develop more
fully and the processes powering the explosions to become more clearly evident.
We compute explosion energy estimates, including the binding energy of the
stellar envelope outside the shock, of 0.34, 0.88, 0.38, and 0.70 B ($10^{51}$
ergs) and increasing at 0.03, 0.15, 0.19, and 0.52 B s$^{-1}$, respectively,
for the 12, 15, 20, and 25 $M_\odot$ models. Three models developed pronounced
prolate shock morphologies, while the 20 $M_\odot$ model, though exhibiting
lobes and accretion streams like the other models, develops an approximately
spherical, off-center shock as the explosion begins and then becomes moderately
prolate $\sim$600 ms after bounce. This reduces the explosion energy relative
to the other models by reducing mass accretion during the critical explosion
power-up phase. We examine the growth of the explosion energy in our models
through detailed analyses of the energy sources and flows. We find that the 12
and 20 $M_\odot$ models have explosion energies comparable to that of the lower
range of observed explosion energies while the 15 and 25 $M_\odot$ models are
within the range of observed explosion energies, particularly considering the
rate at which their explosion energies are increasing. The ejected $^{56}$Ni
masses given by our models are all within observational limits as are the
proto-neutron star masses and kick velocities. (Truncated)
