Objective We model Pickett's Charge at the Battle of Gettysburg to see whether the Confederates could have achieved victory by committing more infantry, executing a better barrage, or facing a weaker defense. Methods Our mathematical modeling is based on Lanchester equations, calibrated using historical army strengths. We weight the Union artillery and infantry two different ways using two sources of data, and so have four versions of the model. Results The models estimate that a successful Confederate charge would have required at least one to three additional brigades. An improved artillery barrage would have reduced these needs by about one brigade. A weaker Union defense could have allowed the charge to succeed as executed. Conclusions The Confederates plausibly had enough troops to take the Union position and alter the battle's outcome, but likely too few to further exploit such a success.