On April 14th…

April 14, 1887: Holmes lay ill in the Hotel Dulong at Lyons. [REIG]

Three days later we were back in Baker Street together, but it was evident that my friend would be much the better for a change, and the thought of a week of springtime in the country was full of attractions to me also. My old friend Colonel Hayter, who had come under my professional care in Afghanistan, had now taken a house near Reigate, in Surrey, and had frequently asked me to come down to him upon a visit. On the last occasion he had remarked that if my friend would only come with me, he would be glad to extend his hospitality to him also.

A little diplomacy was needed, but when Holmes understood that the establishment was a bachelor one, and that he would be allowed the fullest freedom, he fell in with my plans, and a week after our return from Lyons we were under the Colonel’s roof. Hayter was a fine old soldier, who had seen much of the world, and he soon found, as I had expected, that Holmes and he had plenty in common.

On the evening of our arrival we were sitting in the Colonel’s gunroom after dinner, Holmes stretched upon the sofa, while Hayter and I looked over his little armoury of firearms.

Source
A Day by Day Chronology of Sherlock Holmes according to Ziesler and Christ by William S Dorn DWNP, BSI.