Dealing with defiance - tips needed

[Jaffakake]

Ds1 is 3 3/4 and is generally a lovely natured, helpful little man. However recently he is becoming more defiant and I have no idea how to deal with it.
Hes saying no to the silliest things and it's brining us all down.

There is a new baby in the house, but this was starting to happen before he arrived.

An example - nap at lunchtime. Managed to persuade him it was a good idea - he hasnt had to nap for a long time, but recently hes going through a phase of needing more sleep. We'd talked about what we could do this afternoon. However, the deal has always been if he wants to nap in our bed he needs to wee beforehand. If not, he goes in his own bed (expensive mattress!). today it turned into a mega long saga and resulted in me hauling him into the bathroom. Apart from the fact I had a c-section 6 weeks ago, I don't like getting physical and I know its not the answer. Threatened the removal of the activities we were going to do this pm but to no avail. In the end his dad persuaded him to go and within 10 mins he was asleep.

How do we get this done with less agro?

First of all a 3/4 year old is not capable of rationalising his behaviour as in , if I do exactly as Mummy says she will like me better.
He is at the stage where he is looking around at his world and pushing boundaries.
He is too young to be plotting against you to see how miserable he can make you. He is really only a baby himself.

Something has rocked his world and perhaps disturbed him and as he can't articulate his feelings, he is reacting with raw emotion.

You mention a new baby and it is very likely that you are tired out and maybe you are not being as patient as you normally are. We have all been there.
He can't change but will sense the change in you. Hauling and confrontation will only reinforce for him that something is wrong.
His childhood is in your hands. He won't remember your harsh words but he will remember the feeling.
Every time you count to ten and deal with him with extreme patience, you will be rewarded in shed loads when he is older. By being fun, kind patient Mummy instead of grumpy, impatient, shouty, Mummy, you are providing him with a secure and loving childhood. If you do you will be sending him out into the world as a secure human being.
When the roles are reversed and you become old and frail and maybe need him, would you like him to haul you into the bathroom because you have accidently wet yourself or not cleared your plate?
Treat him like you would like to be treated yourself, with respect and patience and you can't go far wrong.
Get a waterproof mattress cover for your bed. Your little boys happiness and wellbeing is worth more than the mattress.
I know you are a really good Mum but you are dog tired and sometime we can't see the wood for the trees. Xx because it is not easy.

Make it fun?

When my kids went through this stage, and all three of them did, I would turn it into a game and tell them they absolutely were not allowed to do whatever I wanted them to do. E. G. It's time for bed now but you must definitely not go and do a wee now. No no, no. No wees. If you do mummy will be very upset. Where are you going? Don't sit on the loo. OK, sit, but no wees. No. Noooooo! Waaah! That is very naughty. Etc. All kids thought it was hilarious and it used to work brilliantly almost every time.