The July 2015 tragedies at two US military facilities in Chattanooga, TN, were just some in a long series of military base shootings across the US. Since WWII, such instances have taken place where soldiers went after their fellow soldiers, or civilians have attempted to enter restricted facilities, with disastrous results. Some tragedies occurred due to race issues, especially in the pre-Cold War segregated military. Others are acts of domestic terror, planned and carried out to inflict maximum damage.
But while what happened in Chattanooga looks to be the work of a radicalized convert to Islam, most of these incidences in the US have nothing to do with Islam, and instead, are the work of soldiers or contractors with undiagnosed mental trauma. Many of the shooters had completed multiple tours of duty in Iraq and Afghanistan, and some had been wounded - suffering blows to the head that might have contributed to their later offenses. And a few look to be crimes of passion or disgruntled former employees out for revenge. As in the civilian world, the motives ranging widely.
This is a list of the known tragedies that occurred on US military bases, including those at Army bases or Naval bases, since WWII.