Government UAS pilot reported they completed a UAS flight without LAANC authorization.

Narrative

While flying a Skydio X10 to record photos of landslides and disaster damage in ZZZ; I launched the drone. Shortly after taking off; one of my coworkers told me to land because he checked the FAA sectional and he realized we were in Class C Airspace. I immediately landed and we debriefed the incident. I checked LAANC and got auto approval for the mission location for a polygon of the area up to 400 feet AGL. This was after I had already launched; flown; and landed in Class C airspace though. This flight was part of a bigger mission on a disaster response incident management team. The team had been flying for two weeks and I had been flying for several days. We had been flying off property along the mountain and driving hundreds of miles a day. This was the third flight of the day in the third mission location. During the briefing in the morning we didn't know each flight location as we were looking for storm damage and flying it when we got there. While we went through a mission briefing and pre flight check list; the mission briefing had been done at the start of the day at the first flight location and not this one. The mission briefing is where we had a discussion about air space but only for the first mission location. As the RPIC it was my responsibility to verify airspace clearance which I did not do. After this incident; as a crew we had a discussion about what happened; why it happened; and how to prevent it from happening moving forward on the deployment and in future missions. We maintained VLOS either with me or with the VO during this and all flights and during this flight saw no other manned aviation. Moving forward; a mission briefing will be done at each new flight location even if it is part of the same overarching mission or even if we only moved a little bit. This will be incorporated into the pre flight checklist as to not be forgotten.