They were stronger. Much stronger. They collapsed for varied reasons, but suffice to say if the British Empire was as big today as it was in its heyday, it would be a larger economy than the US.
Also, no need to say "in conclusion" when the sum total of your argument is a single sentence.
Yeah. Despite Britain's significant fall from grace over the past 100 years, its wealth per capita is still not significantly below that of the US, even now. The US has nothing on how onerous and profiteering the British empire was.
Also, no need to say "in conclusion" when the sum total of your argument is a single sentence.