Today it is not possible to get a war file running within a vsite. It always shows error (destenfeld: I did write some time ago in the mailing list). Either remove the feature or fix it.
https://tomcat.apache.org/tomcat-7.0-doc/appdev/sample/
https://tomcat.apache.org/tomcat-7.0-doc/appdev/sample/sample.war
The sample is included in the tomcat base installaton. So please undeploy first bevor you try to deploy within a site.