To install a web application that serves the root context (/), you need to specify the context mapping using either the application.xml context-root element for the web module specification, or use a context-root element in the war WEB-INF/jboss-web.xml descriptor:

<jboss-web>
    <context-root ></context-root>
</jboss-web>

There is a special naming convention of ROOT.war that can be used to deploy a root context web app without a jboss-web.xml descriptor. This is used to deploy a default root context app. This is found under the jbossweb-tomcat50.sar deployment. This needs to be removed if you are deploying your own root context application.