Strange navigation issue with react-router

I have a fairly basic login setup (code below) with a few components requiring authentication. When I navigate to http://localhost:8000/, it redirects to http://localhost:8000/login and everything is fine. If I then log in, it goes back to http://localhost:8000/ and displays my main component.

However, when I navigate to http://localhost:8000/login directly, it says "Cannot GET /login". Same thing with my "about" component. It does work when I add a pound symbol: http://localhost:8000/#/login. Can anyone explain what's going on?

var React = require('react');
var Main = require('./components/main');
var Login = require('./components/login');
var About = require('./components/about');
var SessionStore = require('./stores/session-store')
import createBrowserHistory from 'history/lib/createBrowserHistory';

import { Router, Route, Link, History, IndexRoute } from 'react-router';

var App = React.createClass({

    render: function() {
        return <div>
          {this.props.children}
        </div>
      }
});

function requireAuth(nextState, replaceState) {
  if(!SessionStore.isLoggedIn()){
    replaceState({ nextPathname: nextState.location.pathname }, '/login');
  }
}

function redirectIfLoggedIn(nextState, replaceState){
  if(SessionStore.isLoggedIn()){
    replaceState({ nextPathname: nextState.location.pathname }, '/');
  }
}

var routes = (
  <Router history={createBrowserHistory()}>
    <Route path="/" component={App}>
      <IndexRoute component={Main} onEnter={requireAuth}/>
      <Route path="login" component={Login} onEnter={redirectIfLoggedIn} />
      <Route path="about" component={About} onEnter={requireAuth} />
    </Route>
  </Router>
)

React.render(routes, document.querySelector('.container'));