FullCalendar Within Twitter Bootstrap Tabs

Dunno why, but for me, using Fullcalendar3 & Bootstrap 4, I had to use :

$('a[data-toggle="tab"]').on('shown.bs.tab', function (e) {
    $('#calendar1').fullCalendar('rerenderEvents');
    $('#calendar2').fullCalendar('rerenderEvents');
});

Afraid I'll answer my own question (it's not against the rules is it ?);

The following code does the trick;

    $(document).ready(function () {
        $('a[data-toggle="tab"]').on('shown.bs.tab', function (e) {
            $('#calendar0').fullCalendar('render');
            $('#calendar1').fullCalendar('render');
        });
        $('#myTab a:first').tab('show');
    });

    <div class="tabbable">
      <ul class="nav nav-tabs" id="myTab">
        <li><a href="#tab_Default" data-toggle="tab"><h5>Default</h5></a></li>
        <li><a href="#tab_Choice1" data-toggle="tab"><h5>Choice 1</h5></a></li>
      </ul>
      <div class="tab-content">
        <div id="tab_Default" class="tab-pane">
            @Html.Partial("_Calendar0")
        </div>
        <div id="tab_Choice1" class="tab-pane">
            @Html.Partial("_Calendar1")
        </div>
      </div>
    </div>

The main problem was that FullCalendar won't load up a Calendar control if it's not on a displayed page.