The RHIC Beam Energy Scan (BES) Program was proposed to look for the turn-off of signatures of the quark gluon plasma (QGP), search for a possible QCD critical point, and study the nature of the phase transition between hadronic and partonic matter. The first phase of the BES program (BES-I) took place from 2010-2016. Several interesting observables studied in BES-I, including the net-proton higher moments and the directed flow of protons, show interesting behavior below 20 GeV and could suggest a transition to a hadron dominated regime. Data from energies lower than 7 GeV could help determine whether these behaviors are indicative of phase transitions or criticality. The goal of the STAR Fixed-Target (FXT) Program is to extend the collision energy range in BES-II to lower energies than is feasible with colliding beams. In order for this program to be approved, it was necessary to demonstrate that STAR could successfully perform measurements in a fixed-target geometry. In this dissertation we present results from the fixed-target pilot run data set collected in 2015 with the STAR detector. The pilot run consisted of 4.5 GeV per nucleon center-of-mass energy Au + Au collisions. The [pi]− spectra and rapidity density are measured from the top 5% most central collisions and found to be comparable to previous results at similar energies from the AGS experiments. Additionally the 4[pi] yield is extracted and found to be 153 +/- 15 (stat) +/- 29 (sys). Together, these and additional results measured by other analyzers from multiple institutions in STAR, demonstrated that STAR can successfully reproduce many physics results from the AGS experiments. This helped convince the Brookhaven Program Advisory Committee (PAC) to include an official FXT program in BES-II, to be conducted in 2019-2021. Specifically, the PAC approved the collection of 100 million events each taken at eight different energies with STAR operating in the fixed-target configuration. This will extend BES-II to center-of-mass energies as low as 3.0 GeV per nucleon, nearly doubling the [mu][subscript B] reach of the BES program and thus broadening our search for interesting transition features in the phase diagram.