Learn Italian: I soldati attraversarono il ponte e conquistarono la città. - The soldiers crossed the bridge and conquered the city.

You drop the -are from the infinitive (attraversare, conquistare) and add the ending -arono. So, attravers- becomes attraversarono and conquist- becomes conquistarono.

Why does this sentence use the passato remoto instead of the passato prossimo (hanno attraversato)?

The passato remoto is used for actions that happened in the distant past and are completely finished, with no connection to the present. This tense is very common in historical writing, literature, and storytelling, which fits perfectly with a sentence about soldiers conquering a city in the past.

Where do I put the emphasis when pronouncing these long verbs?

In the third-person plural of the passato remoto, the stress always falls on the first a of the -arono ending. You pronounce them as at-tra-ver-SA-ro-no and con-qui-STA-ro-no.

I notice ponte ends in -e. Is it masculine or feminine?

Ponte (bridge) is a masculine noun, which is why it uses the article il. Nouns ending in -e can be either masculine or feminine in Italian, so it is always a good idea to memorize them along with their definite article.