Command result of command / request is required

I am trying to create an ASP.NET MVC application with the following CQRS pattern (this is my first taste of CQRS). I understand that the command part has no result. In this answer, @Johannes Rudolph said that if we need a result on the team side, we can create an event and sign to solve the problem. Now suppose we create a login page:

public class AuthController : Controller {

    private ICommandHandler<LoginCommand> _handler;

    public AuthController(ICommandHandler<LoginCommand> handler) {
        _handler = handler;
    }

    public ActionResult Login(LoginModel model) {
        if(ModelState.IsValid) {
            var cmd = new LoginCommand(model.Username, model.Password);
            _handler.Handle(cmd);
            // how to notify about login success or failed?
        }
        return View(model);
    }
}

How can I notify of a successful login command or failed? I know that I can create an event in LoginCommandand subscribe to it in the method above. But my subscription is a separate method and cannot return (for example :) the specified view. Cm:

    public ActionResult Login(LoginModel model) {
        if(ModelState.IsValid) {
            var result = true;
            var cmd = new LoginCommand(model.Username, model.Password);
            cmd.CommandCompleted += e => { result = e; };
            _handler.Handle(cmd);
            // is this correct?
            if(result)
                // redirect to ReturnUrl
            else
                // something else
        }
        return View(model);
    }

? ? ?