There was a lot of harrumphing in Blighty because the French and USA decided they were the only ones who actually did anything at D Day, thus omitting to invite any prominent Brits, like Her Maj for instance. A polite word from that nice Mr Obama into Mr Sarkozy's beautifully tailored ear sorted him out, legend has it.
Obama just forgot he hadn't united humanity in one harmonious brotherhood just yet, and had to invite other nation-states to things for a bit longer. Easy mistake to make.