Calculating the day of the week:

To determine the day of the week for a given date, we can use the concept of a "doomsday," which is a specific day of the week that falls on the same date each year. The doomsday for the Gregorian calendar is Tuesday.

Using this information, we can calculate the day of the week for any given date. Here's how we can determine the day of the week for September 19, 1944, based on the information provided:

Step 1: Find the anchor day:
An anchor day is a known day of the week for a specific date within the same year. In this case, we can use September 19, 1943, as the anchor day.

Since we know that September 15, 1943, was a Wednesday, we can count the number of days between September 15 and September 19:

September 15, 1943 (Wednesday)
September 16, 1943 (Thursday)
September 17, 1943 (Friday)
September 18, 1943 (Saturday)
September 19, 1943 (Sunday)

Therefore, September 19, 1943, was a Sunday.

Step 2: Determine the number of weeks:
Next, we calculate the number of weeks between the anchor day and the desired date. In this case, it's the number of weeks between September 19, 1943, and September 19, 1944.

There are 52 weeks in a year, so the number of weeks is 52.

Step 3: Add the number of days:
To find the day of the week for September 19, 1944, we add the number of days to the anchor day. Since there are 365 days in a year, we divide it by 7 to get the remainder.

365 mod 7 = 1

Adding 1 day to Sunday gives us Monday.

Therefore, September 19, 1944, was a Monday.

Conclusion:

Based on the given information, we can determine that September 19, 1944, was a Monday.