Laravel 5.1 user login not working

I have a registration form which works to register and login user. I use $this->middleware('auth'); in the controllers on protected routes to prompt users to login. The login form passes a POST request to Laravel's AuthController w/ username and password:

 <input type="hidden" name="_token" value="XXXXXXXXXX">
    <div class="widget-content">
        <input type="text" placeholder="Username" name="username">
        <input type="password" placeholder="Password" name="password">
        <input class="btn btn-blue pull-right" type="submit" />
    </div>
</form>

Routes:

//authentication routes
Route::get('auth/login', 'Auth\AuthController@getLogin');
Route::post('auth/login', 'Auth\AuthController@postLogin');
Route::get('auth/logout', 'Auth\AuthController@getLogout');

// Registration routes...
Route::get('auth/register', 'Auth\AuthController@getRegister');
Route::post('auth/register', 'Auth\AuthController@postRegister');

I've tried using the authentication system's off-the-shelf postLogin() functionality, tried passing username, name, email to it without any luck. I tried overriding the parent method like this:

public function postLogin(Request $request)
{
    $username = $request->input('username');
    $password = $request->input('password');

    if (Auth::attempt(['name' => $username, 'password' => $password])) {
        // Authentication passed...
        return redirect('dashboard');
    } else {
        return redirect()->intended('auth/login');
    }
}

via Chebli Mohamed