When Alma-2 was younger, his father was literally a captive of Amulon in the land of Helam. (See Mosiah 24:8-10.) After enduring their burden with patience, they were miraculously delivered and escaped from bondage to the land of Zarahemla, where Alma-2's father become the high priest of the newly established church.
Prior to that, the Nephites who returned to the land of Nephi, led by Zeniff, were ultimately subjected to captivity by the surrounding Lamanites. Also, the wicked King Noah had persecuted Alma-1 and the followers of the church he established in those lands.
When Alma-2 had his miraculous conversion experience, one of the things the angel told him was to "remember the captivity of [his] fathers in the land of Helam and in the land of Nephi" (see Mosiah 27:16.)
Alma-2 kept this charge.
In Alma 5, he begins his great sermon to the people of with these words:
In Alma 36, Alma-2 admonishes his son Helaman-1 to remember the captivity of their fathers:
3 I, Alma, having been consecrated by my father, Alma, to be a high priest over the church of God, he having power and authority from God to do these things, behold, I say unto you that he began to establish a church in the land which was in the borders of Nephi; yea, the land which was called the land of Mormon; yea, and he did baptize his brethren in the waters of Mormon.
4 And behold, I say unto you, they were delivered out of the hands of the people of king Noah, by the mercy and power of God.
5 And behold, after that, they were brought into bondage by the hands of the Lamanites in the wilderness; yea, I say unto you, they were in captivity, and again the Lord did deliver them out of bondage by the power of his word; and we were brought into this land, and here we began to establish the church of God throughout this land also.
6 And now behold, I say unto you, my brethren, you that belong to this church, have you sufficiently retained in remembrance the captivity of your fathers?
2 I would that ye should do as I have done, in remembering the captivity of our fathers; for they were in bondage, and none could deliver them except it was the God of Abraham, and the God of Isaac, and the God of Jacob; and he surely did deliver them in their afflictions.
Years later, Helaman-1 is leading the stripling warriors into battle. These young men have volunteered for combat as a result of their fathers having covenanted never to pick up arms again. Helaman-1 takes to calling them his "sons" (see Alma 56:46). In the very next verse, we learn that:
they did not fear death; and they did think more upon the liberty of their fathers than they did upon their lives;
