Mosiah 10:11 - 10:15

Mosiah 10:11 Now, the Lamanites knew nothing concerning the Lord, nor the strength of the Lord, therefore they depended upon their own strength. Yet they were a strong people, as to the strength of men.

The Lamanites were almost completely ignorant of the Lord being a help to armies in battle. They didn’t even have the concept in their minds. They just depended on their own abilities which are great. They were a force to be reckoned with even if they did not have the Lord to back them up.

Mosiah 10:12 They were a wild, and ferocious, and a blood-thirsty people, believing in the tradition of their fathers, which is this—Believing that they were driven out of the land of Jerusalem because of the iniquities of their fathers, and that they were wronged in the wilderness by their brethren, and they were also wronged while crossing the sea;

The Lamanites are a wild people with little law and relying on their traditions and superstitions for their attitudes and motivations. The main tradition being that their ancestors had to leave Jerusalem because of the false accusations against Laman and Lemuel. That they were falsely accused of evil while in the wilderness and on the voyage across the ocean.

Mosiah 10:13 And again, that they were wronged while in the land of their first inheritance, after they had crossed the sea, and all this because that Nephi was more faithful in keeping the commandments of the Lord—therefore he was favored of the Lord, for the Lord heard his prayers and answered them, and he took the lead of their journey in the wilderness.

They were also wronged in first area they occupied upon arriving in the land of promise. The reason for this so called wrong was that Nephi was more faithful in obeying the Lord and continually seeking His help. He was therefore given leadership of the family in spite of the feeling that Laman and Lemuel thought they should lead being the older brothers.

Mosiah 10:14 And his brethren were wroth with him because they understood not the dealings of the Lord; they were also wroth with him upon the waters because they hardened their hearts against the Lord.

They did not realize that to get to the promise land that they would need the help of the Lord to make the journey. Since they were not asking for any help and even wanted to return to Jerusalem, they lost the leadership position.

Mosiah 10:15 And again, they were wroth with him when they had arrived in the promised land, because they said that he had taken the ruling of the people out of their hands; and they sought to kill him.

When the group arrived in the promised land, Nephi still had leadership which made them angry enough to try to kill him to get him out of the picture so they could take over what they felt was their right as older brothers.
[And having to be subject to their younger brother was more than they could take. They figured that they were deceived by Nephi by some evil process which they could not figure out. They therefore held a grudge against Nephi and all his descendents. It sounds silly, but there are people in this world with the same traditions against other groups.]