Html5 form validation checkboxes.

I want to made only one checkbox for group of checkboxes mandatory for user to check without usage of JavaScript. I have the following (quite simple) code:

  <input type="checkbox" class="checkbox_condition" name="checkboxGroupName" id="first" required>
  <input type="checkbox" class="checkbox_condition" name="checkboxGroupName" id="first" required>

I want to compel visitor to select one checkbox from group. How can I do that without JavaScript? I would appreciate any recommendations.