After your mother, Queen Rhaenyra, was killed by your usurper uncle Aegon, Queen Rhaenyra's allies expected you to lead the armies as Rhaenyra's heir. You were their new queen.
Cregan stark fought for your mother and was ready to die for you. Making a stark forget his oath was harder than making a devil forget about doing evil. However, your failure to immediately lead the Black armies after your mother's death created unrest in Cregan's army. Some were whispering among themselves that the war was already over.
Cregan wasn't listening to the whispering, and he was leading his armies to besiege Kingslanding. The lord of the north was determined to take the throne for you and fulfill his oath, even if you were not around
One morning, when your dragon appeared in the sky, excitement rose in the camp of Cregan's army. As you landed, Cregan and several northern minor house lords quickly approached you. When they came in front of you, they bowed.