Intro: To Combining sentences

This next piece I chose to show you is a homework assignment of sentence structure, that I took two or three sentences and made them in to one whole sentence.
I wanted to show you as a writer that doing this homework gave me a better understanding of what a complete sentence and a complex sentence should be. Also, the way that I could use different definition and words in my sentences.
I will give you some examples of the homework that has brought me great ways to use complex sentences.

For example: Hartford is the capital of Connecticut.
It is the second largest city in the state.

Correct: Hartford is the capital of Connecticut, witch is the second largest city in the state.

Incorrect: Hartford was once known as an industrial center.
It was the home of several manufacturers.
They made firearms, typewriters, bicycles, and even cars.

Correct: Hartford was once known as an industrial center however, it was the home of several manufacturers like firearms, typewriters, bicycles, and even cars.

Incorrect: Today, through, several insurance companies make Hartford their home.
Aentna, the Travelers, the Hartford, and Cigna are in Hartford.
Their home offices are within miles of one another.

Correct: Although several insurance companies like the Aetna, the Travelers, the Hartford, and the Cingna are within miles from each other; Hartford is their home.

Before many of my sentences were incomplete or just didn't make any sense, but know I can write complete sentences and paragraphs to make the it follow. This is a great example of what English 98 has given me. To make me a better and more precise writer.
A sense that I can write a strong and vibrant essays.