This question already has an answer here:
Because Robb needed to cross the Green Fork of the Trident, he pledged to Lord Frey (in his own castle!) to marry one of his daughters/granddaughters. Robb double-crossed Lord Frey, and the rest is history. Anyway...
Did Robb choose to cross at The Twins (Lord Frey's castle) because:
- There were no other possible ways for Robb's small expeditionary force to cross the Green Fork?
- While there are other good places to cross (even large armies), crossing at The Twins allowed Robb to attack the Lannister army from the best tactical position?
If there were no bridges at The Twins, how would the North and South be connected? Only small boats and minor bridges? Or, are there other big crossing points somewhere?