Captain Alex:
Hrm. Harrumph. That's awfully generous of you youngsters, and it absolutely shows the right spirit, but I just can't accept your help in good conscience. These monsters are far too much for our militia to handle, and honestly I can't see you succeeding where my men have failed. Maybe a more experienced band could do the job, but I fear you'd just be throwing your lives away.
Now don't be offended. My men haven't exactly been up to the challenge either. But who knows? You may see more action in the future and come back twice as capable as before! If that happens, and if we're still stuck with this problem, then I'll gladly accept your help.