Just like differentnameforthis , I have one DD who could cope with this, and one who couldn't. It was DD1 who couldn't, and no amount of rocking, shushing, patting, or walking, could get her to sleep in her pram. My ILs have all had lots of DCs, and apparently they would all happily nod off in their prams. So we would always try to stay out later, put her in her pram to sleep, as requested. Late family do's were a nightmare. She would scream if we tried putting her down, but if we let her stay up she was so tired she couldn't function, she couldn't even balance and would whine and cry about everything. She would get so tired she didn't even nod off in the car on the way home. DD2 on the other hand will sleep anywhere if I can rock her and sing Green Day.
The worst (and last!) time we tried to keep DD1 up(19M old), it took me over an hour of rocking and pacing to get her to calm down enough to be put in bed, then about 20 minutes of patting to get her to nod off. This was the child who settled herself to sleep from 2-3 months! The next day she was grumpy all day.
The old lines of "just put her down in her pram", "she'll sleep eventually" and "it's a one off!" really bug me. Not ALL children will be put down in their prams, not ALL children will sleep eventually at an event. It might well be a one off, but what purpose does it serve keeping an overtired fractious child there? The on-duty parent will just spend the whole time trying to soothe the child and won't really be able to socialise anyway, and it sure doesn't benefit the child at all.
I think your DH should be sticking up for what's best for you and your DD here, but if he thinks she should be able to stay out, then tell him he'll be in charge of her at the party, and the next day if she's grumpy, and you'll go have a drink! Highly unfair to ask you to go against your better judgement, then leave you dealing with the fall out.