The guns in the back of the forecastle have defied explanation, but one theory is that they were included to compensate for the guns that were positioned in the aftcastle, aiming forwards, but which would have been obscured due to the angle from which the ship was depicted.[25] The list of ammunition, small firearms, longbows, arrows, pikes, and bills closely matches the archaeological evidence.[26] As the source that is closest in time to the sinking of the Mary Rose, it has been of central importance for the archaeological project, especially in estimating the size of the crew.[27][28][29]