redirecting withErrors not storing errors in session

I am trying to do two steps to validation. First, standard form validation that required fields are filled in. Then, I'm creating a Validator instance and adding an error, then redirecting and including withErrors().

I think I'm doing this all wrong. I'm not getting the errors in the session (I'm testing by logging session every hit to the page).

What am I doing wrong?

        Log::info('session data: '.json_encode($request->session()->all()));

        if(!$request->isMethod('post')) {
            return view('auth.login');
        } else {
            $initialValidate = $this->validate($request, [
                'g-recaptcha-response'  => 'bail|required|captcha',
                'username'                 => 'required|email',
                'password'              => 'required',
            ]);

            $username = $request->get('username', null);
            $password = $request->get('password', null);
            $remember = $request->get('remember', false);

            $validator = Validator::make($request->all(),[]);

            try {
                GlobalHelper::authenticateUser($username, $password);
            } catch(ContactInvalidException $e) {
                $validator->errors()->add('authentication', 'Sorry, your email address or password are incorrect. Please try again.');
            } catch(ContactAuthenticationException $e) {
                $validator->errors()->add('authentication', 'Sorry, your email address or password are incorrect. Please try again.');
            }

            if ($validator->fails()) {
                redirect('user_login')
                    ->withErrors($validator)
                    ->withInput();
            }


        }