about.hbs

{{bd-back-button action='goBack'}}

application.js

import Ember from 'ember';
var inject = Ember.inject;

export default Ember.Route.extend({
  history: inject.service(),

  beforeModel: function(transition) {
    // capture the first page load
    this.get('history').capture(transition);
  },

  actions: {
    willTransition: function(transition) {
      this.get('history').capture(transition);
    },

    goBack: function() {
      var previousTransition = this.get('history.previous');
      if (previousTransition) {
        this.get('history').capture(previousTransition);
        previousTransition.retry();
      } else {
        this.transitionTo('home');
      }
    },
  }
}

bd-back-button.hbs

<i class="bd-icon bd-icon--arrow-left"></i>

bd-back-button.js

import Ember from 'ember';

export default Ember.Component.extend({
  tagName: 'a',
  classNames: ['button button--return'],
  attributeBindings: ['href', 'title'],

  click: function() {
    this.sendAction();
  }
});

Here is an idea giving the history service more responsibility and removing the history concern from the application route. https://gist.github.com/mitchlloyd/9def667b38a8da9558d4