Inside $TOMCAT_HOME/conf/web.xml there is a section called and it looks like this:
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
The default servlet attempts to load the index.* files in the order listed. You may easily override the index.jsp file by creating an index.html file at $TOMCAT_HOME/webapps/ROOT. It's somewhat common for that file to contain a new static home page or a redirect to a servlet's main page. A redirect would look like:
<html>
<head>
<meta http-equiv="refresh" content="0;URL=http://webaddress.com/some/path/to/servlet/homepage/">
</head>
<body>
</body>
</html>