Odysseus had to rescue his men from the lotus-eaters because his men had lost all will of continuing on their journey home. When he sent some men to explore the island, they met the lotus-eaters, which introduced them to the lotus plant. The lotus plant made them forget all about their journey and their families. Odysseus had to drag them onboard, ignoring their wailing cries to be left alone, in order to continue on their journey.
Having the lotus makes you forget and Odysseus couldn't have that as he wanted to get home to his wife and son so he had to <span>carry his men back to the ships and tie them.</span>