the accelerometer gauge or something like that second guess would be the artificial horizon in the cockpit or the climbrate indicator gauge<<<don't know the exact name of that one 
Your Altimeter is the first instrument which will show you a pitch change first! The vertical speed indicator is not reliable because it has "lag" and is used as a reference instrument only! The attitude instrument is a popular answer, but if you are in a combat situation, the attitude gyro may have "tumbled" because you have exceeded the maximum pitch and bank limits of these old "vacuum" type instruments, so the only instrument that you can reliably count on for pitch control is the altimeter. The airspeed indicator is not used for pitch control as it also has "lag" in displaying the current information.
All instrument rated pilots have a "instrument" scan when flying instruments, but when they when through instrument flight training, sooner or later, they had to do "unusual" attitude recoveries, and with only "needle, ball, altimeter and airspeed for reference in recovery, the altimeter is the primary pitch control instrument.
