Perhaps you may want to create a _shoes_by_year partial in the shoe views, and then render the shoe collection:
views/shoes/_shoe.html.erb
<div class=shoe>
<%= shoe.name %>
</div>
views/shoes/_shoes_by_year.html.erb
<% shoes_by_year.each do |release_year, shoes| %>
<div>
<h3><%= release_year.year %></h3>
<%= render 'shoes/shoe', collection: shoes %>
</div>
<% end %>
histories_controller.rb
def show
...
@shoes = @history.shoes.group_by { |shoe| shoe.release.at_beginning_of_year }
end
/views/history/show.html.erb
...
<%= render 'shoes/shoes_by_year', object => @shoes %>