Approved for public release; distribution in unlimited. / This thesis uses an agent-based simulation model named EINSTein to perform an exploratory study on the feasibility of using Littoral Combat Ships (LCSs) to augment or replace the current defenses of Expeditionary Strike Groups (ESG). Specifically, LCS's ability to help defend an ESGs in an anti-access scenario against a high-density small boat attack is simulated. Numbers of CRUDES (CRUiser, DEStroyer, Frigate) ships are removed and LCSs are added to the ESG force structure in varying amounts to identify force mixes that minimize ship losses. In addition, this thesis explores various conceptual capabilities that might be given to LCS. For example, helicopter/Unmanned Combat Aerial Vehicles (helo/UCAVs), Stealth technology, close-in high volume firepower, and 50+ knot sprint capability. Using graphical analysis, analysis of variance, and large-sample comparison tests we find that being able to control aircraft is the most influential factor for minimizing ship losses. Stealth technology is another significant factor, and the combination of the two is highly effective in reducing ship losses. Close-in high volume firepower is effective only when interacting with helo/UCAVs or stealth. 50+ knot sprint capability is potentially detrimental in this scenario. An effective total sum of CRUDES ships and LCS is between five and seven platforms. / http://hdl.handle.net/10945/855 / Lieutenant, United States Navy