1592-1598年日本出兵朝鲜半島之大名及士兵，多來自九州、 中國、四國。這些地區的緯度較朝鲜半島低，氣候較溫暖。因此 半島的冬季對日軍而言，感覺特別寒冷。日軍不習慣此寒天，除 罹患疾病、凍傷或凍死外，另有癘疫流行等。此外，醫生不足， 衛生條件差，醫療缺乏。疾疫與醫療之困境，朝鲜軍與明軍亦相 同。 掌握戰況與交涉和談均需知彼，而取得情報是知彼的方式之 一。除斥候外，日軍主要依賴歸順或被擄朝鲜人及通事。通事則 除對馬人外，另有朝鲜人、明人。朝鲜軍與明軍亦利用俘虜、降 倭及通事等，但雙方均有具雙重間諜身分者。 豐臣秀吉在名護屋、伏見、大坂指揮作戰，半島上的日軍則 接受指令並報告戰況。釜山至漢城間之通訊，繫城、行營、佔領 城邑基本上可作為通訊交通據點。京都—大坂—名護屋間有遞 夫、遞馬、遞船。通信速度，受戰況、季節、義軍抗日等影響。 漢城至名護屋間往返原只需約1個月，至1593年初約需70~90天。 太閣因無法即時確切掌握半島上日軍的動態，對前線諸將的措施僅能探彈性認可。

In the Japanese invasions of Korea, between 1592 and 1598, the daimyos and soldiers were mostly from Kyushu, Chugoku and Shikoku. These regions are located in lower latitude than the war zones in Korean Peninsula; therefore, to the invading Japanese army, the weather was much colder than they were used to, especially in the winter. While the cold winter caused the Japanese army sickness, frostbite, and death, epidemic diseases also spread in the regions. To make situation worse, doctors and medications were insufficient, and hygienic conditions were poor. Similarly, the problems of epidemic disease and poor medication were also found in the Korean and Chinese armies. With regard to information gathering, the Japanese army relied on surrendered or captured Koreans, as well as interpreters. The Korean army and the Chinese army also relied on war prisoners, surrendered Japanese and interpreters; on either side, there were double agents among them. During the invasion, Toyotomi Hideyoshi commanded the Japanese army in Nagoya, Fushimi and Osaka in Japan. As the speed of communication between Japan and the Korean Peninsula was affected by the battlefield situations, seasons, and the resistant of the Korean militia, Toyotomi Hideyoshi often failed to gain efficient control of the Japanese army in Korean Peninsula.