Rendering views for each model in a backbone collection

I'm working on a toy backbone.js application, a library application to perform CRUD operations on a library. Here is the book model and the library collection (of books)

var Book = Backbone.Model.extend({
    url: function() {
        return '/api/books' + this.get('id');
    }
});

var Library = Backbone.Collection.extend({
    model : Book,
    url : '/api/books'
});

This seems pretty straightforward. Next, I obviously want to be able to show the book, so I have a BookView...

var BookView = Backbone.View.extend({
    tagName: 'li',
    render: function() {
        this.$el.html(this.model.get('author'));
        $('#list-of-books').append(this.$el);
    }
});

all the render method does is append an li to the end of an unordered list with an id of list-of-books that is in my html.

Next, unsurprisingly, if I add the following code, I get a list with one item (the name of the author of the book with id=4)

var a_book = new Book();
a_book.url = '/api/books/4';
a_book.fetch({
    success: function() {
        var bookView = new BookView({ model: a_book });
        bookView.render();
    }
});

Here's where I don't understand. I add the following code and nothing happens:

var some_books = new Library();
some_books.fetch();
some_books.forEach(function(book) {
    alert('why is this function not being run');
    var view = new BookView({ model: book });
    view.render();
});

For some reason, I can't even get that loop code to run, I don't even see that alert pop out to the screen. Let me know if you understand what's wrong with this code and how I can make the list render properly. Thanks