Civil War Quests - The Elder Scrolls V: Skyrim wiki

Stormcloaks

If the player chose to follow Ralof to escape Helgen during the quest Unbound, then when following Ralof to Riverwood the player will be invited to join the Stormcloaks and directed to Windhelm.

Imperial Legion

Upon entering an Imperial camp, such as the Pale Imperial Camp, or encountering a group of Imperial soldiers, the player will be invited to join the Imperial legion and directed to Solitude. The quest Join the Imperial Legion is added to the quest log.

Advantages

• Free choice of Light, Medium or Heavy Imperial Armor.
• Upon ranking, random piece of enchanted or unenchanted gear (Scales with player level).
• Ability to purchase home in Solitude