Stage-1 ${\mathrm{NiCl}}_{2}$-graphite intercalation compounds (GIC's) have been prepared under conditions of high temperature and high ${\mathrm{Cl}}_{2}$ pressure. These compounds have a c axis repeat distance of ${\mathrm{I}}_{\mathrm{c}}$=9.36\ifmmode\pm\else\textpm\fi{}0.05 \AA{}, and the intercalate has a rhombohedral interplanar stacking sequence similar to pristine ${\mathrm{NiCl}}_{2}$. Just as with stage-1 ${\mathrm{CoCl}}_{2}$-GIC's, the magnetic behavior of stage-1 ${\mathrm{NiCl}}_{2}$-GIC's appears always to be three dimensional. We interpret the magnetic phase transition at T=22.0\ifmmode\pm\else\textpm\fi{}0.5 K as the N\'eel temperature ${\mathrm{T}}_{\mathrm{N}}$. At lower temperatures, the ac susceptibility shows two magnetic field-induced transitions when a magnetic field is applied in the x-y plane. At T=11.5 K, a temperature much less than ${\mathrm{T}}_{\mathrm{N}}$, the transition field values are ${\mathrm{H}}_{\mathrm{c}1}$=380 Oe and ${\mathrm{H}}_{\mathrm{c}2}$=780 Oe. Compared with similar measurements in stage-2 ${\mathrm{NiCl}}_{2}$-GIC's and pristine ${\mathrm{NiCl}}_{2}$, we estimate that the ratios of the interplanar antiferromagnetic couplings ${\mathrm{J}}_{\mathrm{pristine}}^{\ensuremath{'}}$:${\mathrm{J}}_{\mathrm{stage}--1}^{\ensuremath{'}}$:${\mathrm{J}}_{\mathrm{stage}--2}^{\ensuremath{'}}$ are 720:24:1. These new results now provide us with two families, stage-1 and stage-2 ${\mathrm{CoCl}}_{2}$-GIC's and ${\mathrm{NiCl}}_{2}$-GIC's, from which some general trends about quasi-two-dimensional systems can be inferred.