AngularJS Form Validation - Forcing Validation on Submit

An example of how to force AngularJS to validate after submitting... or at least look like it!

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css">
<form class="form" name="form" ng-app novalidate>
  <div class="form-group">
    <input name="first_name"
          type="text"
          class="form-control"
          ng-model="first_name"
          placeholder="First Name"
          required />
           <p ng-show="form.first_name.$touched && form.first_name.$invalid">
  required
  </p>
  </div>
  <div class="form-group">
    <input name="last_name"
          type="text"
          class="form-control"
          ng-model="last_name"
          placeholder="Last Name"
          required />
  </div>
   
  <button
    type="submit"
    class="btn btn-primary btn-large"
    ng-click="submitted=true">
      Submit
  </button>

<div ng-show="submitted && form.$invalid" class="alert alert-danger">
  <div ng-show="form.first_name.$error.required">
    First Name is Required
  </div>
 
  <div ng-show="form.last_name.$error.required">
    Last Name is Required
  </div>
</div>

</form>