Mastery of the air becomes still more difficult when making a raid, as Lieutenant Rosher did more than once, on the German fortifications along the Belgian coast. ‘A few seconds passed,’ he writes, ‘and the shrapnel burst a good deal short of me, but direction and height perfect. I turned out to sea and put another two miles between me and the coast. By now a regular cannonade was going on. All along the coast the guns were firing hasty, vicious flashes, and then a puff of smoke as the shrapnel burst. I steered a zigzag course and made steadily to sea, climbing hard.’ Of another time when he was under fire and travelling faster than he had ever travelled before, he writes: ‘My chief impressions were the great speed, the flaming bullets streaking by, the incessant rattle of the machine-gun and rifle fire, and one or two shells bursting close by, knocking my machine all sideways and pretty nearly deafening me.’ There is inspiration in the letters, chiefly, perhaps, on account of the fact that they were written for the late Lieutenant Rosher’s dearest friends. He was killed at Dover, while trying a doubtful machine before allowing a fellow-aviator to ascend—a hero’s death. He has been described as one of the most promising officers in the Service. ‘He was not merely a first-class pilot; he was a born organizer and leader of men, and, moreover, he had the heaven-sent gift of being personally popular with all ranks without losing his control over those below him.’ Knowing personally all the senior officers under whom he served, they all had the highest regard for his personal qualities and for his ability as an officer. ‘One may deduce,’ says a writer in the _Aeroplane_, ‘that his letters may fairly be taken as expressing the views, experiences, and feelings of the best class of R.N.A.S. officer, and his father, Mr. Frank Rosher, has done well in publishing them, for they give a vivid and intimate picture of life in the Royal Naval Air Service during the early days of the war. The naval censorship is to be congratulated on having left untouched certain passages which indicate to those who have understanding some of the mistakes made in those early days in the supply or choice of the engines, aeroplanes, and landing grounds. There is no grumbling in the letters themselves, but plain statements are set down.’ The letters begin with Lieutenant Rosher’s early experiences at the Bristol School at Brooklands, whither he went to learn as much as he could between applying for and receiving his commission, and the fact that he took this course is evidence of the keenness which in his short flying life carried him so far in the Service.