They were too many people and badly equipped with supplies. Everything was lacking: water and loads of it(!), food, live stock, ropes, wax, fire wood, oil, clothing, etc. The ones in most need were the women having only the clothing on their backs. The British navy had to distribute sheets so clothing could be made.
In contrast, this new city was very different of what anyone had ever seen in Europe: the climate, vegetation and “naturals” were very different. Many of the people had mestizo origins already and the Portuguese language had evolved to something else; the architecture was random and up the hills, new products and slaves being brought to land, the smells of palm oil and fried fish covered the air and the rich people let themselves be carried by litters.
Príncipe Real arriving in Rio de Janeiro and being hailed by HMS Marlborough, Geoff Hunt.