In recent years, our team has discovered three new phases of ice: ices XIII, XIV and XV. On the basis of calorimetric data and some limited diffraction data collected on GEM we now propose to study the intermediate stages of the ice V to ice XIII and ice VI to ice XV phase transitions on the POLARIS instrument. This study will give detailed insights into the mechanisms of these phase transitions and allow important interpretations of the underlying energetics. Specifically, the questions to be addressed with these experiments are (1) the sequence with which the hydrogen bonds order, (2) how this is connected to the degradation of space group symmetry, (3) how the hydrogen order is established geometrically (e.g. along chains or rings) and (4) if the hydrogen-ordering pathways are different during the initial stages of the phase transitions (e.g. ferroelectric).